| Seq | Timestamp | Type | Name | Duration |
|---|---|---|---|---|
| 0/0 | 2026/10/27 11:05 | flow | patch-triage |
3mArgs:null Results: {
"EnableConfigs": [
"VT",
"FB",
"FB_CORE",
"FRAMEBUFFER_CONSOLE"
],
"FocusSymbols": [
"fb_flashcursor",
"fbcon_add_cursor_work",
"fbcon_del_cursor_work",
"fbcon_del_cursor_work_sync",
"fbcon_release",
"fbcon_cursor",
"cursor_blink_store"
],
"KMSANReasoning": "The patch addresses a concurrency/race condition bug in fbcon's delayed cursor blink work where fb_flashcursor could race with fbcon_del_cursor_work/fbcon_release, potentially leading to use-after-free or improper re-arming of work during teardown.\n\nKASAN vs KMSAN applicability:\n- KASAN is designed to detect use-after-free and out-of-bounds memory accesses. The lifecycle and synchronization issues around `cursor_work` and `struct fbcon_par` tearing down are squarely within KASAN's domain.\n- KMSAN detects reads of uninitialized memory and information leaks to userspace. The patch adds a single boolean field `cursor_blink_on` to `struct fbcon_par`, which is allocated with `kzalloc_obj` (ensuring it is zero-initialized), and alters delayed work cancellation and requeue locking. No data is copied to userspace, no uninitialized memory is read or exposed, and no buffer sizes or bounds are affected.\n\nBecause the changes do not introduce or expose any uninitialized memory hazards, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false,
"Reasoning": "The patch alters concurrency and teardown synchronization for the fbcon cursor blinking delayed work in drivers/video/fbdev/core/fbcon.c. Specifically, it guards work requeuing under console_lock and introduces cursor_blink_on tracking as well as a synchronous delayed work cancellation in fbcon_release to prevent race conditions and potential UAFs. This reachable fbcon driver logic can be exercised in standard virtualized environments via VT ioctls, virtual terminal console operations, and sysfs.",
"WorthFuzzing": true
} |
| 1/1 | 2026/10/27 11:05 | action | read-patch-diff |
0mArgs:null Results: {
"PatchDiff": "commit 82b614d6ff33eebaa547ce0a528a44f180f6e325\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Tue Oct 27 11:05:10 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c\nindex 94abbb5ac7668f..0847dcf18416ab 100644\n--- a/drivers/video/fbdev/core/fbcon.c\n+++ b/drivers/video/fbdev/core/fbcon.c\n@@ -410,7 +410,8 @@ static void fb_flashcursor(struct work_struct *work)\n \tif (par-\u003ecurrcon != -1)\n \t\tvc = vc_cons[par-\u003ecurrcon].d;\n \n-\tif (!vc || !con_is_visible(vc) ||\n+\tif (!par-\u003ecursor_blink_on ||\n+\t !vc || !con_is_visible(vc) ||\n \t fbcon_info_from_console(vc-\u003evc_num) != info ||\n \t vc-\u003evc_deccm != 1) {\n \t\tconsole_unlock();\n@@ -422,25 +423,53 @@ static void fb_flashcursor(struct work_struct *work)\n \tpar-\u003ebitops-\u003ecursor(vc, info, enable,\n \t\t\t get_fg_color(vc, info, c),\n \t\t\t get_bg_color(vc, info, c));\n-\tconsole_unlock();\n \n+\t/*\n+\t * Re-arm under console_lock so that a concurrent\n+\t * fbcon_del_cursor_work() cannot race with this requeue.\n+\t */\n \tqueue_delayed_work(system_power_efficient_wq, \u0026par-\u003ecursor_work,\n \t\t\t par-\u003ecur_blink_jiffies);\n+\tconsole_unlock();\n }\n \n static void fbcon_add_cursor_work(struct fb_info *info)\n {\n \tstruct fbcon_par *par = info-\u003efbcon_par;\n \n-\tif (fbcon_cursor_blink)\n-\t\tqueue_delayed_work(system_power_efficient_wq, \u0026par-\u003ecursor_work,\n-\t\t\t\t par-\u003ecur_blink_jiffies);\n+\tif (!fbcon_cursor_blink)\n+\t\treturn;\n+\n+\tpar-\u003ecursor_blink_on = true;\n+\tqueue_delayed_work(system_power_efficient_wq, \u0026par-\u003ecursor_work,\n+\t\t\t par-\u003ecur_blink_jiffies);\n }\n \n+/*\n+ * Stop the cursor blink.\n+ *\n+ * Does not wait for a callback that is already running, so it is safe to\n+ * call from any context.\n+ *\n+ * console_lock serializes this with the requeue in fb_flashcursor();\n+ * otherwise a running callback could re-arm the work.\n+ */\n static void fbcon_del_cursor_work(struct fb_info *info)\n {\n \tstruct fbcon_par *par = info-\u003efbcon_par;\n \n+\tpar-\u003ecursor_blink_on = false;\n+\tcancel_delayed_work(\u0026par-\u003ecursor_work);\n+}\n+\n+/*\n+ * Stop the cursor blink and wait for a running callback to finish before\n+ * @par is freed. May sleep, only for teardown paths.\n+ */\n+static void fbcon_del_cursor_work_sync(struct fb_info *info)\n+{\n+\tstruct fbcon_par *par = info-\u003efbcon_par;\n+\n \tcancel_delayed_work_sync(\u0026par-\u003ecursor_work);\n }\n \n@@ -765,7 +794,7 @@ static void fbcon_release(struct fb_info *info)\n \tif (info-\u003efbcon_par) {\n \t\tstruct fbcon_par *par = info-\u003efbcon_par;\n \n-\t\tfbcon_del_cursor_work(info);\n+\t\tfbcon_del_cursor_work_sync(info);\n \t\tkfree(par-\u003ecursor_state.mask);\n \t\tkfree(par-\u003ecursor_data);\n \t\tkfree(par-\u003ecursor_src);\ndiff --git a/drivers/video/fbdev/core/fbcon.h b/drivers/video/fbdev/core/fbcon.h\nindex d93a89877d0433..6a2f7f6e5a8c32 100644\n--- a/drivers/video/fbdev/core/fbcon.h\n+++ b/drivers/video/fbdev/core/fbcon.h\n@@ -97,6 +97,7 @@ struct fbcon_par {\n \tint blank_state;\n \tint graphics;\n \tbool initialized;\n+\tbool cursor_blink_on;\n \tint rotate;\n \tchar *cursor_data;\n #ifdef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION\n"
} |
| 2/1 | 2026/10/27 11:05 | agent | patch-evaluator |
3mModel:core Args: null Results: {
"EnableConfigs": [
"VT",
"FB",
"FB_CORE",
"FRAMEBUFFER_CONSOLE"
],
"FocusSymbols": [
"fb_flashcursor",
"fbcon_add_cursor_work",
"fbcon_del_cursor_work",
"fbcon_del_cursor_work_sync",
"fbcon_release",
"fbcon_cursor",
"cursor_blink_store"
],
"Reasoning": "The patch alters concurrency and teardown synchronization for the fbcon cursor blinking delayed work in drivers/video/fbdev/core/fbcon.c. Specifically, it guards work requeuing under console_lock and introduces cursor_blink_on tracking as well as a synchronous delayed work cancellation in fbcon_release to prevent race conditions and potential UAFs. This reachable fbcon driver logic can be exercised in standard virtualized environments via VT ioctls, virtual terminal console operations, and sysfs.",
"WorthFuzzing": true
}Instruction: You are an expert Linux kernel maintainer and security engineer.
Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller.
IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on internal assumptions. You must actively use your code access
tools to inspect the actual source code, callers, and surrounding context.
================================================================================
1. CORE TRIAGE PHILOSOPHY
================================================================================
The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs,
and newly triggered assertions introduced by the patch series.
- REACHABILITY IS THE PRIMARY GATE:
Fuzzing can only discover bugs in code that can actually execute in standard virtualized
environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap).
If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed,
regardless of whether it adds assertions or complex logic.
- DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS:
Patch authors routinely label changes as "cleanups", "refactorings", or state
"No functional change intended". Do NOT take these claims at face value.
Code refactorings that rearrange logic, introduce helper functions, or alter state management
in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs.
If reachable executable code is modified or refactored, it MUST be fuzzed.
- NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED:
When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON*, VM_WARN_ON*,
BUG_ON*, lockdep_assert*) in reachable code paths, it enforces new or stricter invariants.
Even if the author believes the invariant always holds, fuzzing is essential to verify whether
an unusual sequence of operations can violate it.
================================================================================
2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA)
================================================================================
Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories:
- Non-kernel and non-executable changes:
* Modifications to Documentation/, comments, or spelling fixes.
* User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/)
that do not affect the compiled kernel image (vmlinux) or kernel modules.
* Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints
that do not alter control flow or data structures.
* Build system or Kconfig changes that do not alter compiled C logic.
- Structurally unreachable hardware:
* Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed,
ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU.
- Unreachable execution paths:
* Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during
physical PCI hot-unplug or manual sysfs driver unbinding.
* Code paths exclusive to architectures other than the target architecture.
================================================================================
3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA)
================================================================================
Return WorthFuzzing=true whenever the patch touches reachable executable code, including:
- Core Subsystems:
* Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/),
BPF, scheduler, core networking, VFS, or syscall handling.
- Refactorings and Code Cleanups:
* Any restructuring of reachable data structures, helper abstractions, or algorithm flows.
- Runtime Assertions and Defensive Checks:
* Any introduction or alteration of assertions (WARN_ON*, VM_WARN_ON*, BUG_ON*, etc.) in reachable paths.
- Reachable Drivers and Protocols:
* Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.).
================================================================================
4. EXTRACTING FocusSymbols (PREVENTING DILUTION)
================================================================================
When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer:
- AVOID UBIQUITOUS LIFECYCLE HOT-PATHS:
Do NOT list generic, ubiquitous functions called by almost every program in the corpus
(including, but not limited to: general memory allocators and deallocators, page fault
and trap handlers, or core synchronization primitives; this is not an exhaustive list).
Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused",
which severely dilutes fuzzing effort away from the actual changes.
- TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS:
List functions that specifically implement the logic being added or altered, or direct API entrypoints
for the subsystem feature under review.
- HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h):
Compiler-inlined static functions (such as static inlines in mm/*.h or include/linux/*.h) lack
distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters.
If the changes are primarily in static inline helpers, identify non-static, feature-specific caller
functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers).
================================================================================
5. IDENTIFYING EnableConfigs
================================================================================
Identify any specific CONFIG_ options required to properly compile and reach the modified code:
- Inspect Kconfig files and #ifdef guards; do not make assumptions.
- Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed.
- Strip any 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
Prefer calling several tools at the same time to save round-trips.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt: Target architecture: amd64
For your convenience, here is the diff of the changes:
commit 82b614d6ff33eebaa547ce0a528a44f180f6e325
Author: syz-cluster <triage@syzkaller.com>
Date: Tue Oct 27 11:05:10 2026 +0000
syz-cluster: applied patch under review
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 94abbb5ac7668f..0847dcf18416ab 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -410,7 +410,8 @@ static void fb_flashcursor(struct work_struct *work)
if (par->currcon != -1)
vc = vc_cons[par->currcon].d;
- if (!vc || !con_is_visible(vc) ||
+ if (!par->cursor_blink_on ||
+ !vc || !con_is_visible(vc) ||
fbcon_info_from_console(vc->vc_num) != info ||
vc->vc_deccm != 1) {
console_unlock();
@@ -422,25 +423,53 @@ static void fb_flashcursor(struct work_struct *work)
par->bitops->cursor(vc, info, enable,
get_fg_color(vc, info, c),
get_bg_color(vc, info, c));
- console_unlock();
+ /*
+ * Re-arm under console_lock so that a concurrent
+ * fbcon_del_cursor_work() cannot race with this requeue.
+ */
queue_delayed_work(system_power_efficient_wq, &par->cursor_work,
par->cur_blink_jiffies);
+ console_unlock();
}
static void fbcon_add_cursor_work(struct fb_info *info)
{
struct fbcon_par *par = info->fbcon_par;
- if (fbcon_cursor_blink)
- queue_delayed_work(system_power_efficient_wq, &par->cursor_work,
- par->cur_blink_jiffies);
+ if (!fbcon_cursor_blink)
+ return;
+
+ par->cursor_blink_on = true;
+ queue_delayed_work(system_power_efficient_wq, &par->cursor_work,
+ par->cur_blink_jiffies);
}
+/*
+ * Stop the cursor blink.
+ *
+ * Does not wait for a callback that is already running, so it is safe to
+ * call from any context.
+ *
+ * console_lock serializes this with the requeue in fb_flashcursor();
+ * otherwise a running callback could re-arm the work.
+ */
static void fbcon_del_cursor_work(struct fb_info *info)
{
struct fbcon_par *par = info->fbcon_par;
+ par->cursor_blink_on = false;
+ cancel_delayed_work(&par->cursor_work);
+}
+
+/*
+ * Stop the cursor blink and wait for a running callback to finish before
+ * @par is freed. May sleep, only for teardown paths.
+ */
+static void fbcon_del_cursor_work_sync(struct fb_info *info)
+{
+ struct fbcon_par *par = info->fbcon_par;
+
cancel_delayed_work_sync(&par->cursor_work);
}
@@ -765,7 +794,7 @@ static void fbcon_release(struct fb_info *info)
if (info->fbcon_par) {
struct fbcon_par *par = info->fbcon_par;
- fbcon_del_cursor_work(info);
+ fbcon_del_cursor_work_sync(info);
kfree(par->cursor_state.mask);
kfree(par->cursor_data);
kfree(par->cursor_src);
diff --git a/drivers/video/fbdev/core/fbcon.h b/drivers/video/fbdev/core/fbcon.h
index d93a89877d0433..6a2f7f6e5a8c32 100644
--- a/drivers/video/fbdev/core/fbcon.h
+++ b/drivers/video/fbdev/core/fbcon.h
@@ -97,6 +97,7 @@ struct fbcon_par {
int blank_state;
int graphics;
bool initialized;
+ bool cursor_blink_on;
int rotate;
char *cursor_data;
#ifdef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION
|
| 3/2 | 2026/10/27 11:05 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 3978 output: 56 thoughts: 341 Thoughts: **Analyzing the framebuffer console cursor changes** Okay, let's break down these modifications to `fbcon.c` and `fbcon.h`. My initial impression is that this patch is addressing cursor blinking behavior within the framebuffer console. I need to understand the implications of these specific changes. First, within `fbcon.c`, the changes to `fb_flashcursor()` are significant. The addition of the `if (!par->cursor_blink_on || ...)` condition suggests control over the cursor's blinking state. Potentially a mechanism to suspend the blinking or to check if cursor blinking is requested before attempting it. Also, moving the `queue_delayed_work()` call inside `console_lock()` is a concurrency concern. Protecting the queueing operation with a lock is a solid practice to ensure safety. Next, `fbcon_add_cursor_work()` explicitly enables cursor blinking (`par->cursor_blink_on = true;`), and conversely, `fbcon_del_cursor_work()` disables it (`par->cursor_blink_on = false;`) and cancels the associated delayed work. This confirms the direct relationship between these functions and cursor blinking control. The sync version (`fbcon_del_cursor_work_sync()`) is a good addition for situations where you need to guarantee the cancellation is complete before continuing. The most interesting change, though, appears to be the replacement of `fbcon_del_cursor_work()` with `fbcon_del_cursor_work_sync()` in `fbcon_release()`. This strongly implies that, upon console release, a synchronous cancellation of the cursor work is now required. This would be a crucial fix for potential race conditions during driver unloads or console detachments. The synchronous version guarantees that any pending cursor flashes are completed and the work is safely removed before resources are freed. Now I need to grasp the bigger picture. I need to understand *where* these functions are called, the control flow and how they interact. I'll need to use `grepper` or `read-file` to check all the call sites in `fbcon.c` to see how the cursor blinking is used. I need to look for calls to `fbcon_add_cursor_work`, `fbcon_del_cursor_work`, `fb_flashcursor`, etc. Knowing the context will solidify my understanding of the design and the impact of these modifications. |
| 4/2 | 2026/10/27 11:05 | tool | grepper |
0mArgs:{
"Expression": "fbcon_add_cursor_work|fbcon_del_cursor_work|fb_flashcursor",
"PathPrefixes": [
"drivers/video/fbdev/core/fbcon.c"
]
}Results: {
"Output": "drivers/video/fbdev/core/fbcon.c=386=static int get_bg_color(struct vc_data *vc, struct fb_info *info, u16 c)\n--\ndrivers/video/fbdev/core/fbcon.c-390-\ndrivers/video/fbdev/core/fbcon.c:391:static void fb_flashcursor(struct work_struct *work)\ndrivers/video/fbdev/core/fbcon.c-392-{\n--\ndrivers/video/fbdev/core/fbcon.c-428-\t * Re-arm under console_lock so that a concurrent\ndrivers/video/fbdev/core/fbcon.c:429:\t * fbcon_del_cursor_work() cannot race with this requeue.\ndrivers/video/fbdev/core/fbcon.c-430-\t */\n--\ndrivers/video/fbdev/core/fbcon.c-435-\ndrivers/video/fbdev/core/fbcon.c:436:static void fbcon_add_cursor_work(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-437-{\n--\ndrivers/video/fbdev/core/fbcon.c-453- *\ndrivers/video/fbdev/core/fbcon.c:454: * console_lock serializes this with the requeue in fb_flashcursor();\ndrivers/video/fbdev/core/fbcon.c-455- * otherwise a running callback could re-arm the work.\ndrivers/video/fbdev/core/fbcon.c-456- */\ndrivers/video/fbdev/core/fbcon.c:457:static void fbcon_del_cursor_work(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-458-{\n--\ndrivers/video/fbdev/core/fbcon.c-468- */\ndrivers/video/fbdev/core/fbcon.c:469:static void fbcon_del_cursor_work_sync(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-470-{\n--\ndrivers/video/fbdev/core/fbcon.c=785=static void fbcon_release(struct fb_info *info)\n--\ndrivers/video/fbdev/core/fbcon.c-796-\ndrivers/video/fbdev/core/fbcon.c:797:\t\tfbcon_del_cursor_work_sync(info);\ndrivers/video/fbdev/core/fbcon.c-798-\t\tkfree(par-\u003ecursor_state.mask);\n--\ndrivers/video/fbdev/core/fbcon.c=809=static int fbcon_open(struct fb_info *info)\n--\ndrivers/video/fbdev/core/fbcon.c-830-\ndrivers/video/fbdev/core/fbcon.c:831:\tINIT_DELAYED_WORK(\u0026par-\u003ecursor_work, fb_flashcursor);\ndrivers/video/fbdev/core/fbcon.c-832-\tpar-\u003einfo = info;\n--\ndrivers/video/fbdev/core/fbcon.c=924=static int set_con2fb_map(int unit, int newidx, int user)\n--\ndrivers/video/fbdev/core/fbcon.c-952-\ndrivers/video/fbdev/core/fbcon.c:953:\t\tfbcon_add_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-954-\t} else if (vc) {\n--\ndrivers/video/fbdev/core/fbcon.c=1026=static const char *fbcon_startup(void)\n--\ndrivers/video/fbdev/core/fbcon.c-1095-\ndrivers/video/fbdev/core/fbcon.c:1096:\tfbcon_add_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-1097-\treturn display_desc;\n--\ndrivers/video/fbdev/core/fbcon.c=1280=static void fbcon_deinit(struct vc_data *vc)\n--\ndrivers/video/fbdev/core/fbcon.c-1304-\tif (con_is_visible(vc))\ndrivers/video/fbdev/core/fbcon.c:1305:\t\tfbcon_del_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-1306-\n--\ndrivers/video/fbdev/core/fbcon.c=1418=static void fbcon_cursor(struct vc_data *vc, bool enable)\n--\ndrivers/video/fbdev/core/fbcon.c-1429-\tif (vc-\u003evc_cursor_type \u0026 CUR_SW)\ndrivers/video/fbdev/core/fbcon.c:1430:\t\tfbcon_del_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-1431-\telse\ndrivers/video/fbdev/core/fbcon.c:1432:\t\tfbcon_add_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-1433-\n--\ndrivers/video/fbdev/core/fbcon.c=2155=static bool fbcon_switch(struct vc_data *vc)\n--\ndrivers/video/fbdev/core/fbcon.c-2217-\t\tif (old_info != info)\ndrivers/video/fbdev/core/fbcon.c:2218:\t\t\tfbcon_del_cursor_work(old_info);\ndrivers/video/fbdev/core/fbcon.c-2219-\t}\n--\ndrivers/video/fbdev/core/fbcon.c-2221-\tif (!fbcon_is_active(vc, info) || par-\u003eblank_state != FB_BLANK_UNBLANK)\ndrivers/video/fbdev/core/fbcon.c:2222:\t\tfbcon_del_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-2223-\telse\ndrivers/video/fbdev/core/fbcon.c:2224:\t\tfbcon_add_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-2225-\n--\ndrivers/video/fbdev/core/fbcon.c=2296=static bool fbcon_blank(struct vc_data *vc, enum vesa_blank_mode blank,\n--\ndrivers/video/fbdev/core/fbcon.c-2330-\tif (mode_switch || !fbcon_is_active(vc, info) || par-\u003eblank_state != FB_BLANK_UNBLANK)\ndrivers/video/fbdev/core/fbcon.c:2331:\t\tfbcon_del_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-2332-\telse\ndrivers/video/fbdev/core/fbcon.c:2333:\t\tfbcon_add_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-2334-\n--\ndrivers/video/fbdev/core/fbcon.c=3319=static ssize_t cursor_blink_store(struct device *device,\n--\ndrivers/video/fbdev/core/fbcon.c-3342-\t\tfbcon_cursor_blink = true;\ndrivers/video/fbdev/core/fbcon.c:3343:\t\tfbcon_add_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-3344-\t} else {\ndrivers/video/fbdev/core/fbcon.c-3345-\t\tfbcon_cursor_blink = false;\ndrivers/video/fbdev/core/fbcon.c:3346:\t\tfbcon_del_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-3347-\t}\n"
} |
| 5/2 | 2026/10/27 11:05 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 6903 output: 41 thoughts: 198 Thoughts: **Investigating Framebuffer Console Vulnerabilities** Okay, so I'm looking at `fbcon`, the framebuffer console within Linux, and I'm wondering about its accessibility within QEMU and syzkaller. Good news, syzkaller does indeed target it, along with vt (virtual terminal), fbdev, and related components. It's a known bug source! Syzkaller has a good track record of finding issues within `fbcon`, `vgacon`, `dummycon`, `tty`, `vt`, and similar interfaces. The connection is that `fbcon` is reachable through tty/vt ioctls, things like `VT_ACTIVATE`, `VT_SETMODE`, the whole console switching process, sysfs attributes for control like `cursor_blink`, and the framebuffer ioctls themselves: `FBIOGET_VSCREENINFO`/`FBIOPUT_VSCREENINFO`, or even through fbdev ioctls. Let's dive into the code. Time to dig into `drivers/video/fbdev/core/fbcon.c` specifically. I'll need to focus on sections dealing with cursor functionality, particularly around `fb_flashcursor`, `fbcon_add_cursor_work`, `fbcon_del_cursor_work`, and `fbcon_release`. Those seem like good places to begin the vulnerability hunting. |
| 6/2 | 2026/10/27 11:05 | tool | read-file |
0mArgs:{
"File": "drivers/video/fbdev/core/fbcon.c",
"FirstLine": 390,
"LineCount": 60
}Results: {
"Contents": " 390:\t\n 391:\tstatic void fb_flashcursor(struct work_struct *work)\n 392:\t{\n 393:\t\tstruct fbcon_par *par = container_of(work, struct fbcon_par, cursor_work.work);\n 394:\t\tstruct fb_info *info;\n 395:\t\tstruct vc_data *vc = NULL;\n 396:\t\tint c;\n 397:\t\tbool enable;\n 398:\t\tint ret;\n 399:\t\n 400:\t\t/* FIXME: we should sort out the unbind locking instead */\n 401:\t\t/* instead we just fail to flash the cursor if we can't get\n 402:\t\t * the lock instead of blocking fbcon deinit */\n 403:\t\tret = console_trylock();\n 404:\t\tif (ret == 0)\n 405:\t\t\treturn;\n 406:\t\n 407:\t\t/* protected by console_lock */\n 408:\t\tinfo = par-\u003einfo;\n 409:\t\n 410:\t\tif (par-\u003ecurrcon != -1)\n 411:\t\t\tvc = vc_cons[par-\u003ecurrcon].d;\n 412:\t\n 413:\t\tif (!par-\u003ecursor_blink_on ||\n 414:\t\t !vc || !con_is_visible(vc) ||\n 415:\t\t fbcon_info_from_console(vc-\u003evc_num) != info ||\n 416:\t\t vc-\u003evc_deccm != 1) {\n 417:\t\t\tconsole_unlock();\n 418:\t\t\treturn;\n 419:\t\t}\n 420:\t\n 421:\t\tc = scr_readw((u16 *) vc-\u003evc_pos);\n 422:\t\tenable = par-\u003ecursor_flash \u0026\u0026 !par-\u003ecursor_state.enable;\n 423:\t\tpar-\u003ebitops-\u003ecursor(vc, info, enable,\n 424:\t\t\t\t get_fg_color(vc, info, c),\n 425:\t\t\t\t get_bg_color(vc, info, c));\n 426:\t\n 427:\t\t/*\n 428:\t\t * Re-arm under console_lock so that a concurrent\n 429:\t\t * fbcon_del_cursor_work() cannot race with this requeue.\n 430:\t\t */\n 431:\t\tqueue_delayed_work(system_power_efficient_wq, \u0026par-\u003ecursor_work,\n 432:\t\t\t\t par-\u003ecur_blink_jiffies);\n 433:\t\tconsole_unlock();\n 434:\t}\n 435:\t\n 436:\tstatic void fbcon_add_cursor_work(struct fb_info *info)\n 437:\t{\n 438:\t\tstruct fbcon_par *par = info-\u003efbcon_par;\n 439:\t\n 440:\t\tif (!fbcon_cursor_blink)\n 441:\t\t\treturn;\n 442:\t\n 443:\t\tpar-\u003ecursor_blink_on = true;\n 444:\t\tqueue_delayed_work(system_power_efficient_wq, \u0026par-\u003ecursor_work,\n 445:\t\t\t\t par-\u003ecur_blink_jiffies);\n 446:\t}\n 447:\t\n 448:\t/*\n 449:\t * Stop the cursor blink.\n"
} |
| 7/2 | 2026/10/27 11:05 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 8320 output: 41 thoughts: 16 Thoughts: Okay, here's the summary, rendered as a first-person thought process, geared towards an expert: **Focused Review of Specific Code Section** Alright, I need to zero in on a particular section of the codebase, specifically lines 448 through 485. I'm going to take a closer look at this block of code. Given my expertise, I suspect this section could be responsible for something specific I'm trying to identify, or maybe I am looking for a bug here. I'll need to rapidly analyze the logic, variable usage, and potential control flow within those lines to understand their impact. Let's dig in. |
| 8/2 | 2026/10/27 11:05 | tool | read-file |
0mArgs:{
"File": "drivers/video/fbdev/core/fbcon.c",
"FirstLine": 448,
"LineCount": 45
}Results: {
"Contents": " 448:\t/*\n 449:\t * Stop the cursor blink.\n 450:\t *\n 451:\t * Does not wait for a callback that is already running, so it is safe to\n 452:\t * call from any context.\n 453:\t *\n 454:\t * console_lock serializes this with the requeue in fb_flashcursor();\n 455:\t * otherwise a running callback could re-arm the work.\n 456:\t */\n 457:\tstatic void fbcon_del_cursor_work(struct fb_info *info)\n 458:\t{\n 459:\t\tstruct fbcon_par *par = info-\u003efbcon_par;\n 460:\t\n 461:\t\tpar-\u003ecursor_blink_on = false;\n 462:\t\tcancel_delayed_work(\u0026par-\u003ecursor_work);\n 463:\t}\n 464:\t\n 465:\t/*\n 466:\t * Stop the cursor blink and wait for a running callback to finish before\n 467:\t * @par is freed. May sleep, only for teardown paths.\n 468:\t */\n 469:\tstatic void fbcon_del_cursor_work_sync(struct fb_info *info)\n 470:\t{\n 471:\t\tstruct fbcon_par *par = info-\u003efbcon_par;\n 472:\t\n 473:\t\tcancel_delayed_work_sync(\u0026par-\u003ecursor_work);\n 474:\t}\n 475:\t\n 476:\tunsigned char *fbcon_cursor_glyph(const struct vc_font *font, unsigned int cursor_type)\n 477:\t{\n 478:\t\tunsigned int height = font-\u003eheight;\n 479:\t\tunsigned int cursor_size = vc_cursor_valid_size(CUR_SIZE(cursor_type));\n 480:\t\tunsigned char *glyph;\n 481:\t\n 482:\t\tglyph = kmalloc_array(height, vc_font_pitch(font), GFP_ATOMIC);\n 483:\t\tif (!glyph)\n 484:\t\t\treturn NULL;\n 485:\t\n 486:\t\tfont_glyph_cursor(font-\u003ewidth, height,\n 487:\t\t\t\t vc_cursor_start(height, cursor_size),\n 488:\t\t\t\t vc_cursor_end(height, cursor_size), glyph);\n 489:\t\n 490:\t\treturn glyph;\n 491:\t}\n 492:\t\n"
} |
| 9/2 | 2026/10/27 11:05 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 9178 output: 41 thoughts: 13 Thoughts: Okay, let's dive into this. Here's my understanding of what's going on, summarized from the initial prompt: **Analyzing the Function 'fbcon_release'** Alright, the instruction is straightforward: I need to figure out what the function `fbcon_release` is supposed to do. That's the core focus here. My approach will be to examine its code, documentation, or context to determine its purpose and functionality within the system. Let's get to it! |
| 10/2 | 2026/10/27 11:05 | tool | read-file |
0mArgs:{
"File": "drivers/video/fbdev/core/fbcon.c",
"FirstLine": 780,
"LineCount": 40
}Results: {
"Contents": " 780:\t\treturn 0;\n 781:\t}\n 782:\t\n 783:\t#endif /* CONFIG_FB_TILEBLITTING */\n 784:\t\n 785:\tstatic void fbcon_release(struct fb_info *info)\n 786:\t{\n 787:\t\tlock_fb_info(info);\n 788:\t\tif (info-\u003efbops-\u003efb_release)\n 789:\t\t\tinfo-\u003efbops-\u003efb_release(info, 0);\n 790:\t\tunlock_fb_info(info);\n 791:\t\n 792:\t\tmodule_put(info-\u003efbops-\u003eowner);\n 793:\t\n 794:\t\tif (info-\u003efbcon_par) {\n 795:\t\t\tstruct fbcon_par *par = info-\u003efbcon_par;\n 796:\t\n 797:\t\t\tfbcon_del_cursor_work_sync(info);\n 798:\t\t\tkfree(par-\u003ecursor_state.mask);\n 799:\t\t\tkfree(par-\u003ecursor_data);\n 800:\t\t\tkfree(par-\u003ecursor_src);\n 801:\t#ifdef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION\n 802:\t\t\tkfree(par-\u003erotated.buf);\n 803:\t#endif\n 804:\t\t\tkfree(info-\u003efbcon_par);\n 805:\t\t\tinfo-\u003efbcon_par = NULL;\n 806:\t\t}\n 807:\t}\n 808:\t\n 809:\tstatic int fbcon_open(struct fb_info *info)\n 810:\t{\n 811:\t\tstruct fbcon_par *par;\n 812:\t\n 813:\t\tif (!try_module_get(info-\u003efbops-\u003eowner))\n 814:\t\t\treturn -ENODEV;\n 815:\t\n 816:\t\tlock_fb_info(info);\n 817:\t\tif (info-\u003efbops-\u003efb_open \u0026\u0026\n 818:\t\t info-\u003efbops-\u003efb_open(info, 0)) {\n 819:\t\t\tunlock_fb_info(info);\n"
} |
| 11/2 | 2026/10/27 11:05 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 9910 output: 43 thoughts: 353 Thoughts: **Analyzing a Potential Race Condition in the Framebuffer Cursor Blinking** Alright, let's dive into this commit and figure out the reasoning behind these changes. My initial thought is to understand the problem this is solving. Looking at the code, it seems like there might be a race condition. Specifically, I see the changes in `fb_flashcursor` and `fbcon_del_cursor_work`. I notice that `console_unlock()` used to be called *before* the `queue_delayed_work()` call in `fb_flashcursor`. Now it is called after. In `fbcon_del_cursor_work`, the code previously only canceled the delayed work. Now, it sets `par->cursor_blink_on = false;` *before* the cancellation. Ah, I see a potential issue. There's a check in `fb_flashcursor` for `!par->cursor_blink_on` while holding `console_lock`. The addition of `par->cursor_blink_on = false` in `fbcon_del_cursor_work` gives me pause. Could `fbcon_del_cursor_work` be called concurrently with `fb_flashcursor`, potentially leading to a race? I'm thinking, is `fbcon_del_cursor_work` *always* called under `console_lock()`? That's the key question. I need to trace *all* callers of `fbcon_del_cursor_work` to confirm. It is the only way to be sure if this is going to be safe. |
| 12/2 | 2026/10/27 11:05 | tool | grepper |
0mArgs:{
"Expression": "fbcon_del_cursor_work\\(",
"PathPrefixes": [
"drivers/video/fbdev/core/fbcon.c"
]
}Results: {
"Output": "drivers/video/fbdev/core/fbcon.c=391=static void fb_flashcursor(struct work_struct *work)\n--\ndrivers/video/fbdev/core/fbcon.c-428-\t * Re-arm under console_lock so that a concurrent\ndrivers/video/fbdev/core/fbcon.c:429:\t * fbcon_del_cursor_work() cannot race with this requeue.\ndrivers/video/fbdev/core/fbcon.c-430-\t */\n--\ndrivers/video/fbdev/core/fbcon.c=436=static void fbcon_add_cursor_work(struct fb_info *info)\n--\ndrivers/video/fbdev/core/fbcon.c-456- */\ndrivers/video/fbdev/core/fbcon.c:457:static void fbcon_del_cursor_work(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-458-{\n--\ndrivers/video/fbdev/core/fbcon.c=1280=static void fbcon_deinit(struct vc_data *vc)\n--\ndrivers/video/fbdev/core/fbcon.c-1304-\tif (con_is_visible(vc))\ndrivers/video/fbdev/core/fbcon.c:1305:\t\tfbcon_del_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-1306-\n--\ndrivers/video/fbdev/core/fbcon.c=1418=static void fbcon_cursor(struct vc_data *vc, bool enable)\n--\ndrivers/video/fbdev/core/fbcon.c-1429-\tif (vc-\u003evc_cursor_type \u0026 CUR_SW)\ndrivers/video/fbdev/core/fbcon.c:1430:\t\tfbcon_del_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-1431-\telse\n--\ndrivers/video/fbdev/core/fbcon.c=2155=static bool fbcon_switch(struct vc_data *vc)\n--\ndrivers/video/fbdev/core/fbcon.c-2217-\t\tif (old_info != info)\ndrivers/video/fbdev/core/fbcon.c:2218:\t\t\tfbcon_del_cursor_work(old_info);\ndrivers/video/fbdev/core/fbcon.c-2219-\t}\n--\ndrivers/video/fbdev/core/fbcon.c-2221-\tif (!fbcon_is_active(vc, info) || par-\u003eblank_state != FB_BLANK_UNBLANK)\ndrivers/video/fbdev/core/fbcon.c:2222:\t\tfbcon_del_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-2223-\telse\n--\ndrivers/video/fbdev/core/fbcon.c=2296=static bool fbcon_blank(struct vc_data *vc, enum vesa_blank_mode blank,\n--\ndrivers/video/fbdev/core/fbcon.c-2330-\tif (mode_switch || !fbcon_is_active(vc, info) || par-\u003eblank_state != FB_BLANK_UNBLANK)\ndrivers/video/fbdev/core/fbcon.c:2331:\t\tfbcon_del_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-2332-\telse\n--\ndrivers/video/fbdev/core/fbcon.c=3319=static ssize_t cursor_blink_store(struct device *device,\n--\ndrivers/video/fbdev/core/fbcon.c-3345-\t\tfbcon_cursor_blink = false;\ndrivers/video/fbdev/core/fbcon.c:3346:\t\tfbcon_del_cursor_work(info);\ndrivers/video/fbdev/core/fbcon.c-3347-\t}\n"
} |
| 13/2 | 2026/10/27 11:05 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 11652 output: 42 thoughts: 11 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience, and delivered as a first-person summary: **Digging into `cursor_blink_store`** Alright, time to dive in. Let's start by looking at `cursor_blink_store`. It's pretty fundamental, so I need to make sure I have a good grasp on its current state. I'm wondering about potential regressions, performance bottlenecks, and any subtle interactions with other subsystems. I need to quickly ascertain if there have been any recent changes that could impact its behavior. I'll need to check the dependencies, ensure it handles edge cases correctly and verify whether the current implementation is the most performant or elegant solution. Specifically, I should check whether it's thread-safe, and if it's not, what are the implications on any concurrent access scenarios? I also need to verify that its behaviour is correctly specified and that it conforms to my mental model, looking out for any unexpected side effects. |
| 14/2 | 2026/10/27 11:05 | tool | read-file |
0mArgs:{
"File": "drivers/video/fbdev/core/fbcon.c",
"FirstLine": 3319,
"LineCount": 35
}Results: {
"Contents": "3319:\tstatic ssize_t cursor_blink_store(struct device *device,\n3320:\t\t\t\t\t struct device_attribute *attr,\n3321:\t\t\t\t\t const char *buf, size_t count)\n3322:\t{\n3323:\t\tstruct fb_info *info;\n3324:\t\tchar **last = NULL;\n3325:\t\tbool blink;\n3326:\t\tint idx;\n3327:\t\n3328:\t\tconsole_lock();\n3329:\t\tidx = con2fb_map[fg_console];\n3330:\t\n3331:\t\tif (idx == -1 || fbcon_registered_fb[idx] == NULL)\n3332:\t\t\tgoto err;\n3333:\t\n3334:\t\tinfo = fbcon_registered_fb[idx];\n3335:\t\n3336:\t\tif (!info-\u003efbcon_par)\n3337:\t\t\tgoto err;\n3338:\t\n3339:\t\tblink = simple_strtoul(buf, last, 0);\n3340:\t\n3341:\t\tif (blink) {\n3342:\t\t\tfbcon_cursor_blink = true;\n3343:\t\t\tfbcon_add_cursor_work(info);\n3344:\t\t} else {\n3345:\t\t\tfbcon_cursor_blink = false;\n3346:\t\t\tfbcon_del_cursor_work(info);\n3347:\t\t}\n3348:\t\n3349:\terr:\n3350:\t\tconsole_unlock();\n3351:\t\treturn count;\n3352:\t}\n3353:\t\n"
} |
| 15/2 | 2026/10/27 11:05 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 12361 output: 42 thoughts: 21 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience and presented in the first person: **Console Locking Deeper Dive** Right, so I'm trying to wrap my head around this `console_lock` business. Specifically, I'm wondering if all the functions that interact with the console, or anything related to it, are correctly synchronized under this lock. It's a critical area, and a subtle bug here could cause some real headaches, potentially leading to hard-to-debug race conditions or even data corruption on the console output or the input buffers. We know the console is shared between the different processes. My next step is clearly to audit the call-chain. Let's start with a crucial one, `fbcon_deinit`, and follow the lock's presence (or absence!) through that function's execution path. This is a common starting point for a reason, the deinitialization often means shared resources are cleaned. |
| 16/2 | 2026/10/27 11:05 | tool | read-file |
0mArgs:{
"File": "drivers/video/fbdev/core/fbcon.c",
"FirstLine": 1280,
"LineCount": 35
}Results: {
"Contents": "1280:\tstatic void fbcon_deinit(struct vc_data *vc)\n1281:\t{\n1282:\t\tstruct fbcon_display *p = \u0026fb_display[vc-\u003evc_num];\n1283:\t\tstruct fb_info *info;\n1284:\t\tstruct fbcon_par *par;\n1285:\t\tint idx;\n1286:\t\n1287:\t\tfbcon_free_font(p);\n1288:\t\tp-\u003emode = NULL;\n1289:\t\tidx = con2fb_map[vc-\u003evc_num];\n1290:\t\n1291:\t\tif (idx == -1)\n1292:\t\t\tgoto finished;\n1293:\t\n1294:\t\tinfo = fbcon_registered_fb[idx];\n1295:\t\n1296:\t\tif (!info)\n1297:\t\t\tgoto finished;\n1298:\t\n1299:\t\tpar = info-\u003efbcon_par;\n1300:\t\n1301:\t\tif (!par)\n1302:\t\t\tgoto finished;\n1303:\t\n1304:\t\tif (con_is_visible(vc))\n1305:\t\t\tfbcon_del_cursor_work(info);\n1306:\t\n1307:\t\tpar-\u003einitialized = false;\n1308:\tfinished:\n1309:\t\n1310:\t\tfbcon_free_font(p);\n1311:\t\tvc-\u003evc_font.data = NULL;\n1312:\t\n1313:\t\tif (vc-\u003evc_hi_font_mask \u0026\u0026 vc-\u003evc_screenbuf)\n1314:\t\t\tset_vc_hi_font(vc, false);\n"
} |
| 17/2 | 2026/10/27 11:05 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 13090 output: 29 thoughts: 164 Thoughts: **Reaching `fbcon` - A Fuzzing Feasibility Check** Okay, so the question is, can I even get to `fbcon` with my fuzzing setup? That's the real priority. Let's make sure this is actually reachable code that's worth the effort. Right, Section 1, 2, and 3… I need to run through the checklist: Specifically, I'm checking 'Core Subsystems / Reachable Drivers and Protocols'. I'm thinking about drivers that can be accessed through things like virtual buses, consoles, and terminals. And, aha, `fbcon`... that's the framebuffer console! Classic standard Linux kernel stuff, right? It's the standard framebuffer console with virtual terminals and that framebuffer stuff - dummy, bochs, virtio-gpu, that kind of thing. And now I remember, syzkaller has all this extensive documentation and fuzzer descriptions on vt, fbdev, and fbcon ioctls and sysfs! That's definitely a good sign. But wait, I need to check the kernel configuration too. I need to be sure the relevant features are enabled. Let's see... `CONFIG_FRAMEBUFFER_CONSOLE` is the flag I'm looking for. I need to figure out where `fbcon.c` is compiled, just to be sure. |
| 18/2 | 2026/10/27 11:06 | tool | grepper |
0mArgs:{
"Expression": "fbcon\\.o",
"PathPrefixes": [
"drivers/video/"
]
}Results: {
"Output": "drivers/video/fbdev/core/Makefile=15=ifeq ($(CONFIG_FRAMEBUFFER_CONSOLE),y)\ndrivers/video/fbdev/core/Makefile:16:fb-y\t\t\t\t += fbcon.o bitblit.o softcursor.o\ndrivers/video/fbdev/core/Makefile-17-ifeq ($(CONFIG_FB_TILEBLITTING),y)\n"
} |
| 19/2 | 2026/10/27 11:06 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 13669 output: 32 thoughts: 12 Thoughts: Okay, here's my summary, presented as a stream of thought: **Checking Kconfig for FRAMEBUFFER_CONSOLE** Alright, let's get down to brass tacks. I need to make sure `FRAMEBUFFER_CONSOLE` is configured correctly. It's a fundamental piece, and I don't want to waste time chasing down a deeper problem if this basic setting is off. I should be able to quickly navigate Kconfig and check the status of that option. I'm assuming that it is in the menuconfig, but I will need to verify, that is always a safe assumption. I'll need to remember the exact location within the Kconfig hierarchy, but if I can't find it instantly, I know how to use the search functionality efficiently. This is a common requirement in my work. It could be directly enabled, disabled, or set as a module, and that will influence the behavior of the framebuffer console. Time to dive in and confirm its state. This will be a short task, but it is necessary. |
| 20/2 | 2026/10/27 11:06 | tool | grepper |
0mArgs:{
"Expression": "config FRAMEBUFFER_CONSOLE\\b",
"PathPrefixes": [
"drivers/video/"
]
}Results: {
"Output": "drivers/video/console/Kconfig=47=config DUMMY_CONSOLE_ROWS\n--\ndrivers/video/console/Kconfig-57-\ndrivers/video/console/Kconfig:58:config FRAMEBUFFER_CONSOLE\ndrivers/video/console/Kconfig-59-\tbool \"Framebuffer Console support\"\n"
} |
| 21/2 | 2026/10/27 11:06 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 14015 output: 35 thoughts: 20 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: **Diving into the Console Configuration** Okay, let's zero in on the video console configuration, specifically within the kernel's Kconfig file. I'm thinking line 58 in `drivers/video/console/Kconfig` might be a good starting point. I want to quickly refresh my understanding of the relevant options there, specifically those related to… *[the user would then mentally fill in the blanks, based on their expertise, e.g., framebuffer console behavior, VGA text mode support, or specific hardware driver configurations]*. I’m probably looking for dependencies, default values, and potential configuration interplays between the console drivers. |
| 22/2 | 2026/10/27 11:06 | tool | read-file |
0mArgs:{
"File": "drivers/video/console/Kconfig",
"FirstLine": 55,
"LineCount": 40
}Results: {
"Contents": " 55:\t\t monitor.\n 56:\t\t Select 25 if you use a 640x480 resolution by default.\n 57:\t\n 58:\tconfig FRAMEBUFFER_CONSOLE\n 59:\t\tbool \"Framebuffer Console support\"\n 60:\t\tdepends on FB_CORE \u0026\u0026 !UML\n 61:\t\tdefault DRM_FBDEV_EMULATION\n 62:\t\tselect VT_HW_CONSOLE_BINDING\n 63:\t\tselect CRC32\n 64:\t\tselect FONT_SUPPORT\n 65:\t\thelp\n 66:\t\t Low-level framebuffer-based console driver.\n 67:\t\n 68:\tconfig FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION\n 69:\t\tbool \"Enable legacy fbcon hardware acceleration code\"\n 70:\t\tdepends on FRAMEBUFFER_CONSOLE\n 71:\t\tdefault y if PARISC\n 72:\t\tdefault n\n 73:\t\thelp\n 74:\t\t This option enables the fbcon (framebuffer text-based) hardware\n 75:\t\t acceleration for graphics drivers which were written for the fbdev\n 76:\t\t graphics interface.\n 77:\t\n 78:\t\t On modern machines, on mainstream machines (like x86-64) or when\n 79:\t\t using a modern Linux distribution those fbdev drivers usually aren't used.\n 80:\t\t So enabling this option wouldn't have any effect, which is why you want\n 81:\t\t to disable this option on such newer machines.\n 82:\t\n 83:\t\t If you compile this kernel for older machines which still require the\n 84:\t\t fbdev drivers, you may want to say Y.\n 85:\t\n 86:\t\t If unsure, select n.\n 87:\t\n 88:\tconfig FRAMEBUFFER_CONSOLE_DETECT_PRIMARY\n 89:\t bool \"Map the console to the primary display device\"\n 90:\t depends on FRAMEBUFFER_CONSOLE\n 91:\t default n\n 92:\t\thelp\n 93:\t\t If this option is selected, the framebuffer console will\n 94:\t\t automatically select the primary display device (if the architecture\n"
} |
| 23/2 | 2026/10/27 11:06 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 14770 output: 31 thoughts: 17 Thoughts: Okay, here's my summary, presented as a stream of thought: **Digging into the Dependencies of FB_CORE** Alright, time to get my hands dirty. I need to figure out the dependencies and selection criteria associated with `FB_CORE`. This isn't just about knowing what it *uses*, but also what *uses* it. Understanding the downstream implications is just as important as the upstream ones. What components, configurations, or other elements rely on `FB_CORE`? What conditional logic or selection mechanisms determine when it gets included in a build or configuration? This is the starting point for really comprehending its role and potential impact. Let's start peeling back the layers and see what the build system, or configuration files have to say. |
| 24/2 | 2026/10/27 11:06 | tool | grepper |
0mArgs:{
"Expression": "config FB_CORE\\b",
"PathPrefixes": [
"drivers/video/"
]
}Results: {
"Output": "drivers/video/fbdev/core/Kconfig-5-\ndrivers/video/fbdev/core/Kconfig:6:config FB_CORE\ndrivers/video/fbdev/core/Kconfig-7-\tselect VIDEO\n"
} |
| 25/2 | 2026/10/27 11:06 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 15040 output: 37 thoughts: 17 Thoughts: Okay, here's my interpretation of that request, formatted as requested: **Diving into the fbdev Core Kconfig** Alright, let's pull up `drivers/video/fbdev/core/Kconfig`. This is where the magic really begins to happen, isn't it? I need to understand what configuration options are available for framebuffer devices at their core level. This is fundamental. I'm expecting to see dependencies, help texts, and potentially some default values that are going to influence the overall behavior and capabilities of the `fbdev` subsystem. I'm mentally preparing to parse the structure of the file – expecting to see top-level menu entries, individual feature flags controlled by `CONFIG_` variables, and all the usual Kconfig syntax. I'll be looking for relationships between options, the way features are enabled or disabled, and any conditional logic that impacts framebuffer functionality based on hardware or other kernel configurations. I'm also anticipating any `select` statements, which are crucial to understanding how certain features automatically enable or disable dependencies. This is going to be about understanding the building blocks of `fbdev`. Let's see what's in store. |
| 26/2 | 2026/10/27 11:06 | tool | read-file |
0mArgs:{
"File": "drivers/video/fbdev/core/Kconfig",
"FirstLine": 1,
"LineCount": 40
}Results: {
"Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0-only\n 2:\t#\n 3:\t# fbdev core configuration\n 4:\t#\n 5:\t\n 6:\tconfig FB_CORE\n 7:\t\tselect VIDEO\n 8:\t\ttristate\n 9:\t\n 10:\tconfig FB_NOTIFY\n 11:\t\tbool\n 12:\t\n 13:\tconfig FB_DEVICE\n 14:\t\tbool \"Provide legacy /dev/fb* device\"\n 15:\t\tdepends on FB_CORE\n 16:\t\tdefault FB\n 17:\t\thelp\n 18:\t\t Say Y here if you want the legacy /dev/fb* device file and\n 19:\t\t interfaces within sysfs and procfs. It is only required if you\n 20:\t\t have userspace programs that depend on fbdev for graphics output.\n 21:\t\t This does not affect the framebuffer console. If unsure, say N.\n 22:\t\n 23:\tconfig FB_DDC\n 24:\t\ttristate\n 25:\t\tdepends on FB\n 26:\t\tselect I2C_ALGOBIT\n 27:\t\tselect I2C\n 28:\t\n 29:\tconfig FB_CFB_FILLRECT\n 30:\t\ttristate\n 31:\t\tdepends on FB_CORE\n 32:\t\thelp\n 33:\t\t Include the cfb_fillrect function for generic software rectangle\n 34:\t\t filling. This is used by drivers that don't provide their own\n 35:\t\t (accelerated) version.\n 36:\t\n 37:\tconfig FB_CFB_COPYAREA\n 38:\t\ttristate\n 39:\t\tdepends on FB_CORE\n 40:\t\thelp\n"
} |
| 27/2 | 2026/10/27 11:06 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 15795 output: 29 thoughts: 4 Thoughts: Okay, I'm ready. Here's my summary, presented as my internal thought process, assuming I'm an expert in the field: **Internal Reflection on Text Processing and "FB"** Alright, let's break this down. When I see something labeled as `FB`, my mind immediately goes into a few possible directions, given my expertise. Without context, it could be a lot of things. I need more information to really pin it down. * **First, I'm thinking about Facebook (Meta).** Is this referring to data coming from their platform? If so, what aspect? It could be user data, advertising metrics, API interactions, maybe even internal code snippets. The possibilities there are vast and I'll need to know the specific context to understand what type of data from that platform is being utilized. * **Second, I'm considering an initialism, or an obscure variable name.** Is `FB` shorthand for something within a specific project or domain? Could it stand for "Feature Branch," "Feedback," or a technical term specific to a system? I need to analyze its usage and surrounding code to understand the abbreviation. * **Third, is it a file extension or a data format?** I'm thinking about formats such as 'Fixed Block' or something similar. * **Fourth, is it a specific coding environment** such as 'FreeBasic', or 'Flutter', etc. Ultimately, my initial reaction is, "Hmm, `FB`... *what* `FB`? Tell me more!" I'll need surrounding details to properly interpret its meaning and significance. It's a placeholder for meaning until I know its full context. |
| 28/2 | 2026/10/27 11:06 | tool | grepper |
0mArgs:{
"Expression": "config FB\\b",
"PathPrefixes": [
"drivers/video/"
]
}Results: {
"Output": "drivers/video/fbdev/Kconfig-5-\ndrivers/video/fbdev/Kconfig:6:menuconfig FB\ndrivers/video/fbdev/Kconfig-7-\ttristate \"Support for frame buffer device drivers\"\n"
} |
| 29/2 | 2026/10/27 11:06 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 16249 output: 35 thoughts: 15 Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person: **Diving into the Framebuffer Configuration** Right, let's get down to brass tacks. I'm going to take a look at `drivers/video/fbdev/Kconfig`. It's time to refresh my memory on the framebuffer device configuration options. Given the likely scope, I'm expecting this file to define a whole slew of `config` symbols related to various framebuffer drivers, their features (like double buffering, hardware acceleration, etc.), and platform-specific settings. I'll need to pay close attention to the dependencies and default values set. I want to understand how the build system determines which framebuffer drivers are included, which features are enabled by default, and how the overall framebuffer subsystem integrates with other parts of the kernel. This will provide some insight into any new features or changes. I need to understand how the Kconfig file has been set up. I hope that the dependencies are logical and well-commented. I'll be looking for things like: how the generic framebuffer core relates to the drivers, which options are conditionally enabled based on the architecture, and how any new or updated drivers have been integrated into this architecture. I'll pay attention to any dependencies between framebuffer drivers and graphics APIs. |
| 30/2 | 2026/10/27 11:07 | tool | read-file |
0mArgs:{
"File": "drivers/video/fbdev/Kconfig",
"FirstLine": 1,
"LineCount": 35
}Results: {
"Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0-only\n 2:\t#\n 3:\t# fbdev configuration\n 4:\t#\n 5:\t\n 6:\tmenuconfig FB\n 7:\t\ttristate \"Support for frame buffer device drivers\"\n 8:\t\tselect FB_CORE\n 9:\t\tselect FB_NOTIFY\n 10:\t\thelp\n 11:\t\t The frame buffer device provides an abstraction for the graphics\n 12:\t\t hardware. It represents the frame buffer of some video hardware and\n 13:\t\t allows application software to access the graphics hardware through\n 14:\t\t a well-defined interface, so the software doesn't need to know\n 15:\t\t anything about the low-level (hardware register) stuff.\n 16:\t\n 17:\t\t Frame buffer devices work identically across the different\n 18:\t\t architectures supported by Linux and make the implementation of\n 19:\t\t application programs easier and more portable; at this point, an X\n 20:\t\t server exists which uses the frame buffer device exclusively.\n 21:\t\t On several non-X86 architectures, the frame buffer device is the\n 22:\t\t only way to use the graphics hardware.\n 23:\t\n 24:\t\t The device is accessed through special device nodes, usually located\n 25:\t\t in the /dev directory, i.e. /dev/fb*.\n 26:\t\n 27:\t\t You need an utility program called fbset to make full use of frame\n 28:\t\t buffer devices. Please read \u003cfile:Documentation/fb/framebuffer.rst\u003e\n 29:\t\t and the Framebuffer-HOWTO at\n 30:\t\t \u003chttp://www.munted.org.uk/programming/Framebuffer-HOWTO-1.3.html\u003e for more\n 31:\t\t information.\n 32:\t\n 33:\t\t This enables support for native frame buffer device (fbdev) drivers.\n 34:\t\n 35:\t\t The DRM subsystem provides support for emulated frame buffer devices\n"
} |
| 31/2 | 2026/10/27 11:07 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 17096 output: 30 thoughts: 204 Thoughts: Okay, let me break this down. **Investigating Framebuffer Console Dependencies and Syzkaller's Coverage** Right, so `FRAMEBUFFER_CONSOLE` relies on `FB_CORE`. That makes sense. And, of course, it also needs either `FB_DEVICE` or potentially `DRM_FBDEV_EMULATION`, or simply `FB`. Now, I need to figure out if syzkaller is actually targeting `fbcon` and the virtual terminal interfaces. Let's see… the syzkaller configuration usually includes `CONFIG_VT=y`, `CONFIG_FB=y`, and `CONFIG_FRAMEBUFFER_CONSOLE=y`. That's a good start, suggesting it's at least *configured* to potentially interact with these. I need to dig deeper and check the syzkaller syzlang definitions. Do they have anything related to `fbcon`, or sysfs entries like `cursor`, or those vt ioctls? Hmm, a potential snag. I recall that syzkaller's pseudo-syscalls aren't easily grepped in the same way as regular kernel code. But I *do* know the standard interfaces involved: virtual terminals like `/dev/tty0`, `/dev/tty1`, `/dev/vcsa*`, and `/dev/fb0`, and sysfs under `/sys/class/graphics/fbcon/...`. So, those are my targets. Okay, let's zoom in. Specifically, where is that `cursor_blink_store` sysfs path registered? I need to know the origin. |
| 32/2 | 2026/10/27 11:07 | tool | grepper |
0mArgs:{
"Expression": "cursor_blink_store",
"PathPrefixes": [
"drivers/video/"
]
}Results: {
"Output": "drivers/video/fbdev/core/fbcon.c=3294=static ssize_t cursor_blink_show(struct device *device,\n--\ndrivers/video/fbdev/core/fbcon.c-3318-\ndrivers/video/fbdev/core/fbcon.c:3319:static ssize_t cursor_blink_store(struct device *device,\ndrivers/video/fbdev/core/fbcon.c-3320-\t\t\t\t struct device_attribute *attr,\n"
} |
| 33/2 | 2026/10/27 11:07 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 17794 output: 42 thoughts: 31 Thoughts: Okay, here's my summary, presented as a stream of thought: **Diving into `fbcon.c`'s Core** Right, let's get down to it. Time to dig into `drivers/video/fbdev/core/fbcon.c` – specifically, lines 3320 through 3370. This area is likely where the frame buffer console driver handles a critical function or set of functions related to, well, something important. Based on the file and the general structure of the console code, I'd expect it to be a key interaction point. Perhaps something to do with the buffer, drawing elements, managing characters... or maybe even screen updates. Let's see what’s going on. I'm hoping to get a clearer picture of how a specific interaction or bug might be manifesting. |
| 34/2 | 2026/10/27 11:07 | tool | read-file |
0mArgs:{
"File": "drivers/video/fbdev/core/fbcon.c",
"FirstLine": 3335,
"LineCount": 40
}Results: {
"Contents": "3335:\t\n3336:\t\tif (!info-\u003efbcon_par)\n3337:\t\t\tgoto err;\n3338:\t\n3339:\t\tblink = simple_strtoul(buf, last, 0);\n3340:\t\n3341:\t\tif (blink) {\n3342:\t\t\tfbcon_cursor_blink = true;\n3343:\t\t\tfbcon_add_cursor_work(info);\n3344:\t\t} else {\n3345:\t\t\tfbcon_cursor_blink = false;\n3346:\t\t\tfbcon_del_cursor_work(info);\n3347:\t\t}\n3348:\t\n3349:\terr:\n3350:\t\tconsole_unlock();\n3351:\t\treturn count;\n3352:\t}\n3353:\t\n3354:\tstatic DEVICE_ATTR_RW(cursor_blink);\n3355:\tstatic DEVICE_ATTR_RW(rotate);\n3356:\tstatic DEVICE_ATTR_WO(rotate_all);\n3357:\t\n3358:\tstatic struct attribute *fbcon_device_attrs[] = {\n3359:\t\t\u0026dev_attr_cursor_blink.attr,\n3360:\t\t\u0026dev_attr_rotate.attr,\n3361:\t\t\u0026dev_attr_rotate_all.attr,\n3362:\t\tNULL\n3363:\t};\n3364:\t\n3365:\tATTRIBUTE_GROUPS(fbcon_device);\n3366:\t\n3367:\t#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER\n3368:\tstatic void fbcon_register_existing_fbs(struct work_struct *work)\n3369:\t{\n3370:\t\tint i;\n3371:\t\n3372:\t\tconsole_lock();\n3373:\t\n3374:\t\tdeferred_takeover = false;\n"
} |
| 35/2 | 2026/10/27 11:07 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 18560 output: 29 thoughts: 811 Thoughts: **Analyzing the Cursor Blinking Logic in fbcon** Okay, so I'm looking into this `cursor_blink` issue in the framebuffer console driver, `fbcon`. I know that the `cursor_blink` attribute is located at `/sys/class/graphics/fbcon/cursor_blink`. Furthermore, a lot of operations are triggering related callbacks: `fbcon_cursor`, `fbcon_blank`, `fbcon_switch`, and `fbcon_deinit`. Specifically, any writes to `/dev/tty0` or `/dev/vcsa*`, or any VT ioctls, all involve calls to `fbcon_add_cursor_work` and `fbcon_del_cursor_work`. Importantly, `fbcon_release` calls `fbcon_del_cursor_work_sync`. But... what's this patch all about? I need to analyze it to understand the problem it's fixing. The diff seems to be centered around `fb_flashcursor`. Before the patch, the code would unlock the console with `console_unlock()` and *then* re-queue the work with `queue_delayed_work(...)`. The issue was that if `fbcon_del_cursor_work` was called concurrently (during a deinit or teardown), it would call `cancel_delayed_work(&par->cursor_work)`. If `cancel_delayed_work` cancelled the work *before* `fb_flashcursor` had a chance to re-queue it, then the blinking was not stopped correctly. In the original version, `fbcon_release` only called the async `fbcon_del_cursor_work`. This meant the work callback could be executing when the associated parameters (`par`) were freed (`kfree(info->fbcon_par)`), leading to a nasty Use-After-Free condition. The patch fixes this by first checking `!par->cursor_blink_on`. After flashing the cursor, the patch re-queues the delayed work *under the `console_lock`*. This prevents a race where `fbcon_del_cursor_work` can preempt and cancel the work before it's re-queued, ensuring that the blink state is properly managed. Then, `fbcon_release` *now* calls `fbcon_del_cursor_work_sync`, which does `cancel_delayed_work_sync(&par->cursor_work)`. This is a much safer approach. However, I need to verify something: can `cancel_delayed_work_sync` deadlock if `console_lock` is held? I'm going to check the callers of `fbcon_release` to see if the lock is held in any of those contexts. |
| 36/2 | 2026/10/27 11:07 | tool | grepper |
0mArgs:{
"Expression": "fbcon_release",
"PathPrefixes": [
"drivers/video/"
]
}Results: {
"Output": "drivers/video/fbdev/core/fbcon.c=778=static int fbcon_invalid_charcount(struct fb_info *info, unsigned charcount)\n--\ndrivers/video/fbdev/core/fbcon.c-784-\ndrivers/video/fbdev/core/fbcon.c:785:static void fbcon_release(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-786-{\n--\ndrivers/video/fbdev/core/fbcon.c=809=static int fbcon_open(struct fb_info *info)\n--\ndrivers/video/fbdev/core/fbcon.c-826-\tif (!par) {\ndrivers/video/fbdev/core/fbcon.c:827:\t\tfbcon_release(info);\ndrivers/video/fbdev/core/fbcon.c-828-\t\treturn -ENOMEM;\n--\ndrivers/video/fbdev/core/fbcon.c=854=static void con2fb_release_oldinfo(struct vc_data *vc, struct fb_info *oldinfo,\n--\ndrivers/video/fbdev/core/fbcon.c-858-\ndrivers/video/fbdev/core/fbcon.c:859:\tfbcon_release(oldinfo);\ndrivers/video/fbdev/core/fbcon.c-860-\n--\ndrivers/video/fbdev/core/fbcon.c=1257=static void set_vc_hi_font(struct vc_data *vc, bool set);\ndrivers/video/fbdev/core/fbcon.c-1258-\ndrivers/video/fbdev/core/fbcon.c:1259:static void fbcon_release_all(void)\ndrivers/video/fbdev/core/fbcon.c-1260-{\n--\ndrivers/video/fbdev/core/fbcon.c-1275-\t\tif (mapped)\ndrivers/video/fbdev/core/fbcon.c:1276:\t\t\tfbcon_release(info);\ndrivers/video/fbdev/core/fbcon.c-1277-\t}\n--\ndrivers/video/fbdev/core/fbcon.c=1280=static void fbcon_deinit(struct vc_data *vc)\n--\ndrivers/video/fbdev/core/fbcon.c-1316-\tif (!con_is_bound(\u0026fb_con))\ndrivers/video/fbdev/core/fbcon.c:1317:\t\tfbcon_release_all();\ndrivers/video/fbdev/core/fbcon.c-1318-\n"
} |
| 37/2 | 2026/10/27 11:07 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 20643 output: 30 thoughts: 59 Thoughts: Okay, let me think this through. **Investigating a Potential Race Condition in the Framebuffer Console Deinitialization** Right, let's trace this deinitialization process. I need to understand the sequence, so I'll start with `fbcon_deinit`, and follow that chain: `fbcon_deinit` calls `fbcon_release_all`, which in turn calls `fbcon_release`. Got it. Now, the critical question arises: is `fbcon_deinit` being called with the console lock already held? That would be a problem, a serious one. We need to be absolutely certain of this. A lock could result in contention, a nasty race condition. I need to quickly check the call graph to see what's actually calling `fbcon_deinit`. This is where I'll find my answer. Let's see who's invoking this function. This is critical to determine the execution context. |
| 38/2 | 2026/10/27 11:07 | tool | grepper |
0mArgs:{
"Expression": "fbcon_deinit",
"PathPrefixes": [
"drivers/video/"
]
}Results: {
"Output": "drivers/video/fbdev/core/fbcon.c=1259=static void fbcon_release_all(void)\n--\ndrivers/video/fbdev/core/fbcon.c-1279-\ndrivers/video/fbdev/core/fbcon.c:1280:static void fbcon_deinit(struct vc_data *vc)\ndrivers/video/fbdev/core/fbcon.c-1281-{\n--\ndrivers/video/fbdev/core/fbcon.c=3212=static const struct consw fb_con = {\n--\ndrivers/video/fbdev/core/fbcon.c-3215-\t.con_init \t\t= fbcon_init,\ndrivers/video/fbdev/core/fbcon.c:3216:\t.con_deinit \t\t= fbcon_deinit,\ndrivers/video/fbdev/core/fbcon.c-3217-\t.con_clear \t\t= fbcon_clear,\n"
} |
| 39/2 | 2026/10/27 11:07 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 21188 output: 31 thoughts: 39 Thoughts: Here's my summary, as though I'm thinking through this process: **Investigating the `con_deinit` Call in `vt.c`** Okay, so I see `con_deinit` is being called from `drivers/tty/vt/vt.c`. That's the starting point. My next step is clear: I need to understand the *why* and *when* of this call. Specifically, I'm going to track down all the other call sites within `vt.c` that invoke `con_deinit`. I need to understand the control flow and what triggers this de-initialization routine to be called within the virtual terminal driver. Identifying the callers will provide insight into the context and potential issues related to resource cleanup or shutdown procedures. Time to dive into the code. |
| 40/2 | 2026/10/27 11:07 | tool | grepper |
0mArgs:{
"Expression": "con_deinit",
"PathPrefixes": [
"drivers/tty/vt/"
]
}Results: {
"Output": "drivers/tty/vt/vt.c=1171=static void visual_deinit(struct vc_data *vc)\ndrivers/tty/vt/vt.c-1172-{\ndrivers/tty/vt/vt.c:1173:\tvc-\u003evc_sw-\u003econ_deinit(vc);\ndrivers/tty/vt/vt.c-1174-\tmodule_put(vc-\u003evc_sw-\u003eowner);\n--\ndrivers/tty/vt/vt.c=4106=static int do_bind_con_driver(const struct consw *csw, int first, int last,\n--\ndrivers/tty/vt/vt.c-4168-\t\told_was_color = vc-\u003evc_can_do_color;\ndrivers/tty/vt/vt.c:4169:\t\tvc-\u003evc_sw-\u003econ_deinit(vc);\ndrivers/tty/vt/vt.c-4170-\t\tvc-\u003evc_origin = (unsigned long)vc-\u003evc_screenbuf;\n"
} |
| 41/2 | 2026/10/27 11:07 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 21688 output: 31 thoughts: 19 Thoughts: Here's my thought process, as if I were considering this issue: **Investigating `visual_deinit` and Console Lock** Okay, so I need to verify something critical here. I'm thinking, let's nail down whether the `visual_deinit` function is being called while the `console_lock` is held. That's a potential area for race conditions or other issues if we're not careful. I need to confirm the locking context in that part of the code, to ensure thread safety and prevent any unexpected behavior during shutdown or deinitialization. A quick check of the call stack around `visual_deinit` and how the lock is being used is in order. |
| 42/2 | 2026/10/27 11:07 | tool | grepper |
0mArgs:{
"Expression": "visual_deinit",
"PathPrefixes": [
"drivers/tty/vt/"
]
}Results: {
"Output": "drivers/tty/vt/vt.c=1141=static void visual_init(struct vc_data *vc, int num, bool init)\n--\ndrivers/tty/vt/vt.c-1170-\ndrivers/tty/vt/vt.c:1171:static void visual_deinit(struct vc_data *vc)\ndrivers/tty/vt/vt.c-1172-{\n--\ndrivers/tty/vt/vt.c=1196=int vc_allocate(unsigned int currcons)\t/* return 0 on success */\n--\ndrivers/tty/vt/vt.c-1249-err_free:\ndrivers/tty/vt/vt.c:1250:\tvisual_deinit(vc);\ndrivers/tty/vt/vt.c-1251-\tif (*vc-\u003euni_pagedict_loc)\n--\ndrivers/tty/vt/vt.c=1470=struct vc_data *vc_deallocate(unsigned int currcons)\n--\ndrivers/tty/vt/vt.c-1481-\t\tvcs_remove_sysfs(currcons);\ndrivers/tty/vt/vt.c:1482:\t\tvisual_deinit(vc);\ndrivers/tty/vt/vt.c-1483-\t\tcon_free_unimap(vc);\n"
} |
| 43/2 | 2026/10/27 11:07 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 22221 output: 27 thoughts: 1912 Thoughts: **Analysis of fbcon Concurrency and Fuzzing Strategy** Okay, so `vc_deallocate` calls `fbcon_release`, which can potentially hold `console_lock`. Meanwhile, `fb_flashcursor`, which handles the cursor blinking logic, also attempts to acquire `console_lock` using `console_trylock()`. This is clever; if `console_lock` is already held, `fb_flashcursor` just returns immediately. The use of `cancel_delayed_work_sync` ensures that any currently running instance of `fb_flashcursor` finishes before, say, `vc_deallocate` frees its resources. We're dealing with subtle concurrency, and this area definitely warrants a closer look, especially with respect to the lock acquisition order and the cursor blink logic. Given that fbcon is accessible in standard virtualized environments and reachable via VT ioctls, console writes, sysfs, and fbdev ioctls, *WorthFuzzing* is unequivocally set to *true*. The fbcon subsystem's presence in QEMU/syzkaller VMs and its interaction with user-space make it a prime target. Now, let's nail down the *FocusSymbols*. The instructions say we need to avoid ubiquitous lifecycle functions and instead target specific feature logic and entry points. The patch touches a number of symbols in `fbcon.c`: `fb_flashcursor`, `fbcon_add_cursor_work`, `fbcon_del_cursor_work`, `fbcon_del_cursor_work_sync`, and `fbcon_release`. I need to choose carefully, avoiding the more ubiquitous ones. `fb_flashcursor` is a work function and is definitely not inlined. It's the core of the cursor blinking logic and, critically, it's where the locking order change occurs. This is a must-include in the *FocusSymbols*. `fbcon_release` is static, which means it isn't inlined, and is called from `con2fb_release_oldinfo`, `fbcon_release_all`, and `fbcon_open`. Then `fbcon_add_cursor_work` and `fbcon_del_cursor_work`, they are static and, potentially, inlined. Let's dig deeper: I see calls to them from `fbcon_cursor`, `fbcon_switch`, `fbcon_blank`, `fbcon_deinit`, `cursor_blink_store`, `set_con2fb_map`, and `fbcon_startup`. Those functions, in turn, are called via the `consw` table. Meaning they are not inlined. Let's carefully pick specific and non-ubiquitous entrypoints. So, I'm thinking the following symbols in *FocusSymbols*: * `fb_flashcursor` - This is the primary function being changed and relates to locking and cursor blink logic. It's crucial. * `fbcon_cursor` - Part of the `consw` table, specific to cursor handling and not ubiquitous. * `cursor_blink_store` - The sysfs entry point for controlling cursor blinking, directly tied to the feature. * `fbcon_del_cursor_work` - Specifically for removing cursor blink work. * `fbcon_add_cursor_work` - Specifically for adding cursor blink work. * `fbcon_release` - The release function for the console, and it interacts with the cursor work. These seem to be the most targeted entrypoints. Finally, let's verify that the required config is enabled. Given that `fbcon.c` depends on `CONFIG_FRAMEBUFFER_CONSOLE` which is present in the `drivers/video/fbdev/core/` `Makefile`, and framebuffer console is enabled, the build should be good. |
| 44/2 | 2026/10/27 11:07 | tool | grepper |
0mArgs:{
"Expression": "fbdev",
"PathPrefixes": [
"drivers/video/"
]
}Results: {
"Output": "\nFull output is too long, showing 200 out of 3109 lines.\nUse more precise expression or PathPrefixes if possible.\n\nNumber of matching lines per file (57 files in total):\ndrivers/video/Kconfig:1\ndrivers/video/Makefile:1\ndrivers/video/aperture.c:1\ndrivers/video/cmdline.c:2\ndrivers/video/console/Kconfig:3\ndrivers/video/fbdev/Kconfig:21\ndrivers/video/fbdev/arcfb.c:1\ndrivers/video/fbdev/arkfb.c:1\ndrivers/video/fbdev/aty/aty128fb.c:2\ndrivers/video/fbdev/aty/radeon_base.c:1\ndrivers/video/fbdev/au1100fb.c:107\ndrivers/video/fbdev/au1200fb.c:46\ndrivers/video/fbdev/broadsheetfb.c:1\ndrivers/video/fbdev/controlfb.c:1\ndrivers/video/fbdev/core/Kconfig:2\ndrivers/video/fbdev/core/fb_defio.c:1\ndrivers/video/fbdev/core/fb_fillrect.h:1\ndrivers/video/fbdev/core/fb_internal.h:1\ndrivers/video/fbdev/core/fbcon.c:3\ndrivers/video/fbdev/core/fbsysfs.c:1\ndrivers/video/fbdev/hecubafb.c:1\ndrivers/video/fbdev/i740fb.c:1\ndrivers/video/fbdev/kyro/Makefile:1\ndrivers/video/fbdev/kyro/fbdev.c:1\ndrivers/video/fbdev/macfb.c:1\ndrivers/video/fbdev/metronomefb.c:1\ndrivers/video/fbdev/mmp/Kconfig:3\ndrivers/video/fbdev/neofb.c:1\ndrivers/video/fbdev/ocfb.c:63\ndrivers/video/fbdev/omap/hwa742.c:42\ndrivers/video/fbdev/omap/lcd_mipid.c:4\ndrivers/video/fbdev/omap/lcdc.c:38\ndrivers/video/fbdev/omap/omapfb.h:6\ndrivers/video/fbdev/omap/omapfb_main.c:281\ndrivers/video/fbdev/omap/sossi.c:17\ndrivers/video/fbdev/omap2/Kconfig:1\ndrivers/video/fbdev/omap2/omapfb/Kconfig:2\ndrivers/video/fbdev/omap2/omapfb/omapfb-ioctl.c:32\ndrivers/video/fbdev/omap2/omapfb/omapfb-main.c:156\ndrivers/video/fbdev/omap2/omapfb/omapfb-sysfs.c:26\ndrivers/video/fbdev/omap2/omapfb/omapfb.h:14\ndrivers/video/fbdev/platinumfb.c:1\ndrivers/video/fbdev/riva/Makefile:1\ndrivers/video/fbdev/riva/fbdev.c:1\ndrivers/video/fbdev/riva/rivafb-i2c.c:1\ndrivers/video/fbdev/s3fb.c:1\ndrivers/video/fbdev/sa1100fb.c:1\ndrivers/video/fbdev/sis/sis_main.c:1\ndrivers/video/fbdev/skeletonfb.c:6\ndrivers/video/fbdev/smscufx.c:4\n... and 7 more files\n\ndrivers/video/Kconfig=47=menu \"Frame buffer Devices\"\ndrivers/video/Kconfig:48:source \"drivers/video/fbdev/Kconfig\"\ndrivers/video/Kconfig-49-endmenu\n--\ndrivers/video/Makefile=16=obj-y\t\t\t\t += backlight/\ndrivers/video/Makefile-17-\ndrivers/video/Makefile:18:obj-y\t\t\t\t += fbdev/\ndrivers/video/Makefile-19-\n--\ndrivers/video/aperture.c=302=EXPORT_SYMBOL(aperture_remove_conflicting_devices);\n--\ndrivers/video/aperture.c-318- * WARNING: Apparently we must remove graphics drivers before calling\ndrivers/video/aperture.c:319: * this helper. Otherwise the vga fbdev driver falls over if\ndrivers/video/aperture.c-320- * we have vgacon configured.\n--\ndrivers/video/cmdline.c-2-/*\ndrivers/video/cmdline.c:3: * Based on the fbdev code in drivers/video/fbdev/core/fb_cmdline:\ndrivers/video/cmdline.c-4- *\n--\ndrivers/video/cmdline.c=33=static const char *__video_get_option_string(const char *name)\n--\ndrivers/video/cmdline.c-68- * Looks up the video= options for the given name. Names are connector\ndrivers/video/cmdline.c:69: * names with DRM, or driver names with fbdev. If no video option for\ndrivers/video/cmdline.c-70- * the name has been specified, the function returns the global video=\n--\ndrivers/video/console/Kconfig=68=config FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION\n--\ndrivers/video/console/Kconfig-74-\t This option enables the fbcon (framebuffer text-based) hardware\ndrivers/video/console/Kconfig:75:\t acceleration for graphics drivers which were written for the fbdev\ndrivers/video/console/Kconfig-76-\t graphics interface.\n--\ndrivers/video/console/Kconfig-78-\t On modern machines, on mainstream machines (like x86-64) or when\ndrivers/video/console/Kconfig:79:\t using a modern Linux distribution those fbdev drivers usually aren't used.\ndrivers/video/console/Kconfig-80-\t So enabling this option wouldn't have any effect, which is why you want\n--\ndrivers/video/console/Kconfig-83-\t If you compile this kernel for older machines which still require the\ndrivers/video/console/Kconfig:84:\t fbdev drivers, you may want to say Y.\ndrivers/video/console/Kconfig-85-\n--\ndrivers/video/fbdev/Kconfig-2-#\ndrivers/video/fbdev/Kconfig:3:# fbdev configuration\ndrivers/video/fbdev/Kconfig-4-#\n--\ndrivers/video/fbdev/Kconfig=6=menuconfig FB\n--\ndrivers/video/fbdev/Kconfig-32-\ndrivers/video/fbdev/Kconfig:33:\t This enables support for native frame buffer device (fbdev) drivers.\ndrivers/video/fbdev/Kconfig-34-\ndrivers/video/fbdev/Kconfig-35-\t The DRM subsystem provides support for emulated frame buffer devices\ndrivers/video/fbdev/Kconfig:36:\t on top of KMS drivers, but this option allows legacy fbdev drivers to\ndrivers/video/fbdev/Kconfig-37-\t be enabled as well.\n--\ndrivers/video/fbdev/Kconfig=53=config FB_SVGALIB\n--\ndrivers/video/fbdev/Kconfig-56-\thelp\ndrivers/video/fbdev/Kconfig:57:\t Common utility functions useful to fbdev drivers of VGA-based\ndrivers/video/fbdev/Kconfig-58-\t cards.\n--\ndrivers/video/fbdev/Kconfig=137=config FB_SA1100\n--\ndrivers/video/fbdev/Kconfig-142-\t This is a framebuffer device for the SA-1100 LCD Controller.\ndrivers/video/fbdev/Kconfig:143:\t See \u003chttp://www.linux-fbdev.org/\u003e for information on framebuffer\ndrivers/video/fbdev/Kconfig-144-\t devices.\n--\ndrivers/video/fbdev/Kconfig=587=config FB_PVR2\n--\ndrivers/video/fbdev/Kconfig-606-\t the meaning of XXX can be found at the end of the main source file\ndrivers/video/fbdev/Kconfig:607:\t (\u003cfile:drivers/video/fbdev/pvr2fb.c\u003e). Please see the file\ndrivers/video/fbdev/Kconfig-608-\t \u003cfile:Documentation/fb/pvr2fb.rst\u003e.\n--\ndrivers/video/fbdev/Kconfig=668=config FB_NVIDIA_I2C\n--\ndrivers/video/fbdev/Kconfig-676-\ndrivers/video/fbdev/Kconfig:677:\t Because fbdev-2.6 requires that drivers must be able to\ndrivers/video/fbdev/Kconfig-678-\t independently validate video mode parameters, you should say Y\n--\ndrivers/video/fbdev/Kconfig=716=config FB_RIVA_I2C\n--\ndrivers/video/fbdev/Kconfig-724-\ndrivers/video/fbdev/Kconfig:725:\t Because fbdev-2.6 requires that drivers must be able to\ndrivers/video/fbdev/Kconfig-726-\t independently validate video mode parameters, you should say Y\n--\ndrivers/video/fbdev/Kconfig=894=config FB_MATROX_MAVEN\n--\ndrivers/video/fbdev/Kconfig-904-\t secondary head output is blanked while you are in X. With XFree\ndrivers/video/fbdev/Kconfig:905:\t 3.9.17 preview you can use both heads if you use SVGA over fbdev or\ndrivers/video/fbdev/Kconfig:906:\t the fbdev driver on first head and the fbdev driver on second head.\ndrivers/video/fbdev/Kconfig-907-\n--\ndrivers/video/fbdev/Kconfig=1080=config FB_SAVAGE_I2C\n--\ndrivers/video/fbdev/Kconfig-1088-\ndrivers/video/fbdev/Kconfig:1089:\t Because fbdev-2.6 requires that drivers must be able to\ndrivers/video/fbdev/Kconfig-1090-\t independently validate video mode parameters, you should say Y\n--\ndrivers/video/fbdev/Kconfig=1160=config FB_VIA_X_COMPATIBILITY\n--\ndrivers/video/fbdev/Kconfig-1164-\t framebuffer to avoid negative impact on the OpenChrome X server.\ndrivers/video/fbdev/Kconfig:1165:\t If you use any X server other than fbdev you should enable this\ndrivers/video/fbdev/Kconfig-1166-\t otherwise it should be safe to disable it and allow using all\n--\ndrivers/video/fbdev/Kconfig=1382=config FB_WMT_GE_ROPS\n--\ndrivers/video/fbdev/Kconfig-1388-\ndrivers/video/fbdev/Kconfig:1389:source \"drivers/video/fbdev/geode/Kconfig\"\ndrivers/video/fbdev/Kconfig-1390-\n--\ndrivers/video/fbdev/Kconfig=1571=config FB_SMSCUFX\n--\ndrivers/video/fbdev/Kconfig-1577-\t This is a kernel framebuffer driver for SMSC UFX USB devices.\ndrivers/video/fbdev/Kconfig:1578:\t Supports fbdev clients like xf86-video-fbdev, kdrive, fbi, and\ndrivers/video/fbdev/Kconfig:1579:\t mplayer -vo fbdev. Supports both UFX6000 (USB 2.0) and UFX7000\ndrivers/video/fbdev/Kconfig-1580-\t (USB 3.0) devices.\n--\ndrivers/video/fbdev/Kconfig=1583=config FB_UDL\n--\ndrivers/video/fbdev/Kconfig-1590-\t This is a kernel framebuffer driver for DisplayLink USB devices.\ndrivers/video/fbdev/Kconfig:1591:\t Supports fbdev clients like xf86-video-fbdev, kdrive, fbi, and\ndrivers/video/fbdev/Kconfig:1592:\t mplayer -vo fbdev. Supports all USB 2.0 era DisplayLink devices.\ndrivers/video/fbdev/Kconfig-1593-\t To compile as a module, choose M here: the module name is udlfb.\n--\ndrivers/video/fbdev/Kconfig=1789=config FB_SM712\n--\ndrivers/video/fbdev/Kconfig-1800-\ndrivers/video/fbdev/Kconfig:1801:source \"drivers/video/fbdev/omap/Kconfig\"\ndrivers/video/fbdev/Kconfig:1802:source \"drivers/video/fbdev/omap2/Kconfig\"\ndrivers/video/fbdev/Kconfig:1803:source \"drivers/video/fbdev/mmp/Kconfig\"\ndrivers/video/fbdev/Kconfig-1804-\ndrivers/video/fbdev/Kconfig:1805:source \"drivers/video/fbdev/core/Kconfig\"\n--\ndrivers/video/fbdev/arcfb.c=611=module_exit(arcfb_exit);\ndrivers/video/fbdev/arcfb.c-612-\ndrivers/video/fbdev/arcfb.c:613:MODULE_DESCRIPTION(\"fbdev driver for Arc monochrome LCD board\");\ndrivers/video/fbdev/arcfb.c-614-MODULE_AUTHOR(\"Jaya Kumar\");\n--\ndrivers/video/fbdev/arkfb.c=103=MODULE_LICENSE(\"GPL\");\ndrivers/video/fbdev/arkfb.c:104:MODULE_DESCRIPTION(\"fbdev driver for ARK 2000PV\");\ndrivers/video/fbdev/arkfb.c-105-\n--\ndrivers/video/fbdev/aty/aty128fb.c=2297=static int aty128_pci_suspend_late(struct device *dev, pm_message_t state)\n--\ndrivers/video/fbdev/aty/aty128fb.c-2345-\ndrivers/video/fbdev/aty/aty128fb.c:2346:\t/* We need a way to make sure the fbdev layer will _not_ touch the\ndrivers/video/fbdev/aty/aty128fb.c-2347-\t * framebuffer before we put the chip to suspend state. On 2.4, I\ndrivers/video/fbdev/aty/aty128fb.c-2348-\t * used dummy fb ops, 2.5 need proper support for this at the\ndrivers/video/fbdev/aty/aty128fb.c:2349:\t * fbdev level\ndrivers/video/fbdev/aty/aty128fb.c-2350-\t */\n--\ndrivers/video/fbdev/aty/radeon_base.c=2242=static int radeonfb_pci_register(struct pci_dev *pdev,\n--\ndrivers/video/fbdev/aty/radeon_base.c-2454-\ndrivers/video/fbdev/aty/radeon_base.c:2455:\t/* Register with fbdev layer */\ndrivers/video/fbdev/aty/radeon_base.c-2456-\tret = register_framebuffer(info);\n--\ndrivers/video/fbdev/au1100fb.c=419=static int au1100fb_fb_blank(int blank_mode, struct fb_info *fbi)\ndrivers/video/fbdev/au1100fb.c-420-{\ndrivers/video/fbdev/au1100fb.c:421:\tstruct au1100fb_device *fbdev = to_au1100fb_device(fbi);\ndrivers/video/fbdev/au1100fb.c-422-\n--\ndrivers/video/fbdev/au1100fb.c-428-\t\t/* Turn on panel */\ndrivers/video/fbdev/au1100fb.c:429:\t\tfbdev-\u003eregs-\u003elcd_control |= LCD_CONTROL_GO;\ndrivers/video/fbdev/au1100fb.c-430-\t\twmb(); /* drain writebuffer */\n--\ndrivers/video/fbdev/au1100fb.c-436-\t\t/* Turn off panel */\ndrivers/video/fbdev/au1100fb.c:437:\t\tfbdev-\u003eregs-\u003elcd_control \u0026= ~LCD_CONTROL_GO;\ndrivers/video/fbdev/au1100fb.c-438-\t\twmb(); /* drain writebuffer */\n--\ndrivers/video/fbdev/au1100fb.c-450-\t */\ndrivers/video/fbdev/au1100fb.c:451:static int au1100fb_setmode(struct au1100fb_device *fbdev)\ndrivers/video/fbdev/au1100fb.c-452-{\n--\ndrivers/video/fbdev/au1100fb.c-456-\ndrivers/video/fbdev/au1100fb.c:457:\tif (!fbdev)\ndrivers/video/fbdev/au1100fb.c-458-\t\treturn -EINVAL;\ndrivers/video/fbdev/au1100fb.c-459-\ndrivers/video/fbdev/au1100fb.c:460:\tinfo = \u0026fbdev-\u003einfo;\ndrivers/video/fbdev/au1100fb.c-461-\ndrivers/video/fbdev/au1100fb.c-462-\t/* Update var-dependent FB info */\ndrivers/video/fbdev/au1100fb.c:463:\tif (panel_is_active(fbdev-\u003epanel) || panel_is_color(fbdev-\u003epanel)) {\ndrivers/video/fbdev/au1100fb.c-464-\t\tif (info-\u003evar.bits_per_pixel \u003c= 8) {\n--\ndrivers/video/fbdev/au1100fb.c-486-\t\t\t/* non-palettized */\ndrivers/video/fbdev/au1100fb.c:487:\t\t\tindex = (fbdev-\u003epanel-\u003econtrol_base \u0026 LCD_CONTROL_SBPPF_MASK) \u003e\u003e LCD_CONTROL_SBPPF_BIT;\ndrivers/video/fbdev/au1100fb.c-488-\t\t\tinfo-\u003evar.red = rgb_bitfields[index][0];\n--\ndrivers/video/fbdev/au1100fb.c-502-\tinfo-\u003escreen_size = info-\u003efix.line_length * info-\u003evar.yres_virtual;\ndrivers/video/fbdev/au1100fb.c:503:\tinfo-\u003evar.rotate = ((fbdev-\u003epanel-\u003econtrol_base\u0026LCD_CONTROL_SM_MASK) \\\ndrivers/video/fbdev/au1100fb.c-504-\t\t\t\t\u003e\u003e LCD_CONTROL_SM_BIT) * 90;\n--\ndrivers/video/fbdev/au1100fb.c-506-\t/* Determine BPP mode and format */\ndrivers/video/fbdev/au1100fb.c:507:\tfbdev-\u003eregs-\u003elcd_control = fbdev-\u003epanel-\u003econtrol_base;\ndrivers/video/fbdev/au1100fb.c:508:\tfbdev-\u003eregs-\u003elcd_horztiming = fbdev-\u003epanel-\u003ehorztiming;\ndrivers/video/fbdev/au1100fb.c:509:\tfbdev-\u003eregs-\u003elcd_verttiming = fbdev-\u003epanel-\u003everttiming;\ndrivers/video/fbdev/au1100fb.c:510:\tfbdev-\u003eregs-\u003elcd_clkcontrol = fbdev-\u003epanel-\u003eclkcontrol_base;\ndrivers/video/fbdev/au1100fb.c:511:\tfbdev-\u003eregs-\u003elcd_intenable = 0;\ndrivers/video/fbdev/au1100fb.c:512:\tfbdev-\u003eregs-\u003elcd_intstatus = 0;\ndrivers/video/fbdev/au1100fb.c:513:\tfbdev-\u003eregs-\u003elcd_dmaaddr0 = LCD_DMA_SA_N(fbdev-\u003efb_phys);\ndrivers/video/fbdev/au1100fb.c-514-\ndrivers/video/fbdev/au1100fb.c:515:\tif (panel_is_dual(fbdev-\u003epanel)) {\ndrivers/video/fbdev/au1100fb.c-516-\t\t/* Second panel display seconf half of screen if possible,\n\n"
} |
| 45/2 | 2026/10/27 11:07 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 30188 output: 36 thoughts: 16 Thoughts: Here's a summary of my thought process, as requested: **Diving into the Framebuffer Core Makefile** Okay, so I need to understand something related to the framebuffer device driver core, right? My initial instinct is to dig into the `Makefile` located in `drivers/video/fbdev/core/`. This is the logical starting point. The `Makefile` is where all the build rules for this part of the driver are defined, and it’s going to give me a good overview of the source files involved, any dependencies, and likely some crucial build options or flags relevant to the overall architecture. I anticipate I'll find include directives pointing to relevant headers, object file dependencies, and probably some conditional compilation based on kernel configuration options. This will quickly give me a sense of the scope of the problem I'm investigating and hopefully help point me to the specific pieces of code that matter most. |
| 46/2 | 2026/10/27 11:08 | tool | read-file |
0mArgs:{
"File": "drivers/video/fbdev/core/Makefile",
"FirstLine": 1,
"LineCount": 40
}Results: {
"Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0\n 2:\tobj-$(CONFIG_FB_NOTIFY) += fb_notify.o\n 3:\tobj-$(CONFIG_FB_CORE) += fb.o\n 4:\tfb-y := fb_info.o \\\n 5:\t fbmem.o fbcmap.o \\\n 6:\t modedb.o fbcvt.o fb_cmdline.o\n 7:\tifdef CONFIG_FB\n 8:\tfb-y += fb_backlight.o fbmon.o\n 9:\tendif\n 10:\tfb-$(CONFIG_FB_DEFERRED_IO) += fb_defio.o\n 11:\tfb-$(CONFIG_FB_DEVICE) += fb_chrdev.o \\\n 12:\t fb_procfs.o \\\n 13:\t fbsysfs.o\n 14:\t\n 15:\tifeq ($(CONFIG_FRAMEBUFFER_CONSOLE),y)\n 16:\tfb-y\t\t\t\t += fbcon.o bitblit.o softcursor.o\n 17:\tifeq ($(CONFIG_FB_TILEBLITTING),y)\n 18:\tfb-y\t\t\t\t += tileblit.o\n 19:\tendif\n 20:\tifeq ($(CONFIG_FRAMEBUFFER_CONSOLE_ROTATION),y)\n 21:\tfb-y\t\t\t\t += fbcon_rotate.o fbcon_cw.o fbcon_ud.o \\\n 22:\t\t\t\t\t fbcon_ccw.o\n 23:\tendif\n 24:\tendif\n 25:\t\n 26:\tfb-$(CONFIG_LOGO)\t\t += fb_logo.o\n 27:\t\n 28:\tobj-$(CONFIG_FB_CFB_FILLRECT) += cfbfillrect.o\n 29:\tobj-$(CONFIG_FB_CFB_COPYAREA) += cfbcopyarea.o\n 30:\tobj-$(CONFIG_FB_CFB_IMAGEBLIT) += cfbimgblt.o\n 31:\tobj-$(CONFIG_FB_IOMEM_FOPS) += fb_io_fops.o\n 32:\tobj-$(CONFIG_FB_SYS_FILLRECT) += sysfillrect.o\n 33:\tobj-$(CONFIG_FB_SYS_COPYAREA) += syscopyarea.o\n 34:\tobj-$(CONFIG_FB_SYS_IMAGEBLIT) += sysimgblt.o\n 35:\tobj-$(CONFIG_FB_SYSMEM_FOPS) += fb_sys_fops.o\n 36:\tobj-$(CONFIG_FB_SVGALIB) += svgalib.o\n 37:\tobj-$(CONFIG_FB_DDC) += fb_ddc.o\n"
} |
| 47/2 | 2026/10/27 11:08 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 31137 output: 33 thoughts: 186 Thoughts: **Analyzing the Framebuffer Configuration** Okay, so I'm looking at this build configuration, specifically how `fbcon.o` gets compiled. I see this line: `obj-$(CONFIG_FB_CORE) += fb.o` and this conditional: `ifeq ($(CONFIG_FRAMEBUFFER_CONSOLE),y) fb-y += fbcon.o bitblit.o softcursor.o`. Right away, it's clear that both `FB_CORE` and `FRAMEBUFFER_CONSOLE` need to be enabled for `fbcon.o` to be built. But, hang on, there's the `VT` dependency too – I know virtual terminal console drivers like `consw` rely on VT, so that's a factor. Let me check the Kconfig file for `FRAMEBUFFER_CONSOLE`, it's probably `drivers/video/console/Kconfig`. Ah, here it is: `depends on FB_CORE && !UML`, and it `select`s `VT_HW_CONSOLE_BINDING`, `CRC32`, and `FONT_SUPPORT`. That confirms my assumptions. Now, where is this `drivers/video/console/Kconfig` file actually included? I need to trace back its inclusion to understand the complete dependency chain. |
| 48/2 | 2026/10/27 11:08 | tool | grepper |
0mArgs:{
"Expression": "source.*drivers/video/console/Kconfig",
"PathPrefixes": [
"drivers/"
]
}Results: {
"Output": "drivers/video/Kconfig=84=if VT\ndrivers/video/Kconfig:85:\tsource \"drivers/video/console/Kconfig\"\ndrivers/video/Kconfig-86-endif\n"
} |
| 49/2 | 2026/10/27 11:08 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 31686 output: 217 thoughts: 1050 Thoughts: **Analyzing FBcon Cursor Blinking and Teardown for Fuzzing** Okay, let's break this down. First, I need to confirm the build requirements. Since the code modifies `fbcon` related to the cursor, I know `VT` must be enabled. Checking `drivers/video/Kconfig`, that makes sense. And, of course, `FB_CORE` needs to be enabled, which is selected by `FB` or built directly. Plus, `FRAMEBUFFER_CONSOLE`. Let me make sure `CONFIG_FB` is also set. So, the minimal requirements are `VT`, `FB_CORE`, `FRAMEBUFFER_CONSOLE`, and `FB`. Good, got that. Now, let's identify the key symbols in this patch. I've got a list here: 1. `fb_flashcursor`: This is the delayed workqueue callback, handling the cursor blink. Modified with checks for `cursor_blink_on` and re-arming the delayed work under `console_lock`. 2. `fbcon_add_cursor_work`: This sets `par->cursor_blink_on = true` and queues the cursor delayed work. 3. `fbcon_del_cursor_work`: This sets `par->cursor_blink_on = false` and cancels the cursor delayed work. 4. `fbcon_del_cursor_work_sync`: The new function that cancels the work synchronously. 5. `fbcon_release`: This is modified to use `fbcon_del_cursor_work_sync` before freeing `par`. 6. `fbcon_cursor`: This is the VT cursor callback calling the add/del work functions. 7. `cursor_blink_store`: This is the sysfs entry point for toggling `fbcon` cursor blink. Are any of these ubiquitous? No. - `fb_flashcursor`: Only triggered by the fbcon cursor blink timer. Definitely not ubiquitous. - `fbcon_add_cursor_work`, `fbcon_del_cursor_work`, `fbcon_del_cursor_work_sync`: They're specific helpers. - `fbcon_release`: Called when the fbcon device is released or unmapped. Still, not ubiquitous, but important. - `fbcon_cursor`: Called when the console cursor updates, specifically under vt/fbcon. - `cursor_blink_store`: The sysfs entry point for cursor blinking. Wait, are the helpers (`fbcon_add_cursor_work`, `fbcon_del_cursor_work`, `fbcon_del_cursor_work_sync`) static? Let's check if the compiler inlines them. `fbcon_del_cursor_work_sync` looks like it only has a single call site in `fbcon_release`, so it's very likely inlined. `fbcon_del_cursor_work` has a few call sites (deinit, cursor, switch, blank, cursor_blink_store). `fbcon_add_cursor_work` has similar, multiple call sites (set_con2fb_map, startup, cursor, switch, blank, cursor_blink_store). `fb_flashcursor` is a work handler, so its address is taken - it will never be inlined. `fbcon_cursor` is a struct consw method. `cursor_blink_store` is a sysfs store callback. `fbcon_release` is static, called from 3 places. `fbcon_switch` is a struct consw method. `fbcon_blank` is a struct consw method. Okay, so I've confirmed that includes: - `fb_flashcursor` - `fbcon_add_cursor_work` - `fbcon_del_cursor_work` - `fbcon_del_cursor_work_sync` - `fbcon_release` - `fbcon_cursor` - `cursor_blink_store` Now, let's verify all the requirements and guidelines for fuzzing this. - Architecture: amd64. That is what I am working with. - `WorthFuzzing`: Yes, absolutely. This patch modifies the fbcon cursor blinking and teardown synchronization to prevent races and use-after-free conditions. These are high-value targets. The modified code in `fbdev/core/fbcon.c` is accessible from user space via VT/TTY ioctls, console switching, and sysfs, and runs in standard virtualized QEMU environments. - `FocusSymbols`: Verified. I' |
| 50/2 | 2026/10/27 11:08 | tool | set-results |
0mArgs:{
"EnableConfigs": [
"VT",
"FB",
"FB_CORE",
"FRAMEBUFFER_CONSOLE"
],
"FocusSymbols": [
"fb_flashcursor",
"fbcon_add_cursor_work",
"fbcon_del_cursor_work",
"fbcon_del_cursor_work_sync",
"fbcon_release",
"fbcon_cursor",
"cursor_blink_store"
],
"Reasoning": "The patch alters concurrency and teardown synchronization for the fbcon cursor blinking delayed work in drivers/video/fbdev/core/fbcon.c. Specifically, it guards work requeuing under console_lock and introduces cursor_blink_on tracking as well as a synchronous delayed work cancellation in fbcon_release to prevent race conditions and potential UAFs. This reachable fbcon driver logic can be exercised in standard virtualized environments via VT ioctls, virtual terminal console operations, and sysfs.",
"WorthFuzzing": true
}Results: {
"EnableConfigs": [
"VT",
"FB",
"FB_CORE",
"FRAMEBUFFER_CONSOLE"
],
"FocusSymbols": [
"fb_flashcursor",
"fbcon_add_cursor_work",
"fbcon_del_cursor_work",
"fbcon_del_cursor_work_sync",
"fbcon_release",
"fbcon_cursor",
"cursor_blink_store"
],
"Reasoning": "The patch alters concurrency and teardown synchronization for the fbcon cursor blinking delayed work in drivers/video/fbdev/core/fbcon.c. Specifically, it guards work requeuing under console_lock and introduces cursor_blink_on tracking as well as a synchronous delayed work cancellation in fbcon_release to prevent race conditions and potential UAFs. This reachable fbcon driver logic can be exercised in standard virtualized environments via VT ioctls, virtual terminal console operations, and sysfs.",
"WorthFuzzing": true
} |
| 51/1 | 2026/10/27 11:08 | action | If |
0mArgs:{
"WorthFuzzing": true
}Results: null |
| 52/2 | 2026/10/27 11:08 | agent | kmsan-evaluator |
0mModel:core Args: null Results: {
"KMSANReasoning": "The patch addresses a concurrency/race condition bug in fbcon's delayed cursor blink work where fb_flashcursor could race with fbcon_del_cursor_work/fbcon_release, potentially leading to use-after-free or improper re-arming of work during teardown.\n\nKASAN vs KMSAN applicability:\n- KASAN is designed to detect use-after-free and out-of-bounds memory accesses. The lifecycle and synchronization issues around `cursor_work` and `struct fbcon_par` tearing down are squarely within KASAN's domain.\n- KMSAN detects reads of uninitialized memory and information leaks to userspace. The patch adds a single boolean field `cursor_blink_on` to `struct fbcon_par`, which is allocated with `kzalloc_obj` (ensuring it is zero-initialized), and alters delayed work cancellation and requeue locking. No data is copied to userspace, no uninitialized memory is read or exposed, and no buffer sizes or bounds are affected.\n\nBecause the changes do not introduce or expose any uninitialized memory hazards, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
}Instruction: You are an expert Linux kernel security engineer specializing in kernel memory
error detectors (KASAN and KMSAN). Your job is to review the provided patch series and
determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer)
fuzzing session in addition to standard KASAN fuzzing.
CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN:
- Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable
a comprehensive suite of debugging tools and sanitizers, including KASAN
(out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP
(locking bugs and deadlocks), UB-sanitizers, and memory corruption checks.
- KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap,
or page allocations) and kernel-to-user memory info-leaks.
Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN,
LOCKDEP, OR OTHER STANDARD BUG DETECTORS.
A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY
set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks
that are detected ONLY by KMSAN.
Look holistically at the patch series and surrounding code. Even if no direct
uninitialized field accesses or new buffer allocations are added in the diff itself,
a patch may alter control flow, bounds checking, or data length calculations in ways
that change how the rest of the code operates on existing buffers (e.g. allowing
uninitialized stack/heap memory to be read, copied to user space, or used in control
flow). Do not hesitate to use your code access tools to inspect the surrounding code,
called functions, and callers.
Set NeedsKMSAN=true ONLY IF the patch introduces or modifies:
1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb
attributes, ioctl output arguments, socket options, or BPF buffers) where fields
or structure padding might not be fully initialized/zeroed.
2. Conditional logic or branching that depends on potentially uninitialized variables
or struct fields.
3. Allocation or initialization of complex data structures where uninitialized fields
could be read later in reachable code paths.
4. Bounds checks, lengths, or logic in a way that allows surrounding code to access
uninitialized bytes of existing buffers.
Set NeedsKMSAN=false IF:
- The code changes primarily risk out-of-bounds access, array overflows, NULL pointer
dereferences, locking deadlocks, or use-after-free bugs (these are already caught
by KASAN, LOCKDEP, or standard bug detectors).
- All stack/heap structures touched or introduced by the patch are fully zeroed
or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied.
- The patch does not introduce any risk of uninitialized memory usage or info-leaks.
Use your code access tools to inspect the surrounding code if necessary, then provide
detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch.
Prefer calling several tools at the same time to save round-trips.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt: Target architecture: amd64
For your convenience, here is the diff of the changes:
commit 82b614d6ff33eebaa547ce0a528a44f180f6e325
Author: syz-cluster <triage@syzkaller.com>
Date: Tue Oct 27 11:05:10 2026 +0000
syz-cluster: applied patch under review
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 94abbb5ac7668f..0847dcf18416ab 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -410,7 +410,8 @@ static void fb_flashcursor(struct work_struct *work)
if (par->currcon != -1)
vc = vc_cons[par->currcon].d;
- if (!vc || !con_is_visible(vc) ||
+ if (!par->cursor_blink_on ||
+ !vc || !con_is_visible(vc) ||
fbcon_info_from_console(vc->vc_num) != info ||
vc->vc_deccm != 1) {
console_unlock();
@@ -422,25 +423,53 @@ static void fb_flashcursor(struct work_struct *work)
par->bitops->cursor(vc, info, enable,
get_fg_color(vc, info, c),
get_bg_color(vc, info, c));
- console_unlock();
+ /*
+ * Re-arm under console_lock so that a concurrent
+ * fbcon_del_cursor_work() cannot race with this requeue.
+ */
queue_delayed_work(system_power_efficient_wq, &par->cursor_work,
par->cur_blink_jiffies);
+ console_unlock();
}
static void fbcon_add_cursor_work(struct fb_info *info)
{
struct fbcon_par *par = info->fbcon_par;
- if (fbcon_cursor_blink)
- queue_delayed_work(system_power_efficient_wq, &par->cursor_work,
- par->cur_blink_jiffies);
+ if (!fbcon_cursor_blink)
+ return;
+
+ par->cursor_blink_on = true;
+ queue_delayed_work(system_power_efficient_wq, &par->cursor_work,
+ par->cur_blink_jiffies);
}
+/*
+ * Stop the cursor blink.
+ *
+ * Does not wait for a callback that is already running, so it is safe to
+ * call from any context.
+ *
+ * console_lock serializes this with the requeue in fb_flashcursor();
+ * otherwise a running callback could re-arm the work.
+ */
static void fbcon_del_cursor_work(struct fb_info *info)
{
struct fbcon_par *par = info->fbcon_par;
+ par->cursor_blink_on = false;
+ cancel_delayed_work(&par->cursor_work);
+}
+
+/*
+ * Stop the cursor blink and wait for a running callback to finish before
+ * @par is freed. May sleep, only for teardown paths.
+ */
+static void fbcon_del_cursor_work_sync(struct fb_info *info)
+{
+ struct fbcon_par *par = info->fbcon_par;
+
cancel_delayed_work_sync(&par->cursor_work);
}
@@ -765,7 +794,7 @@ static void fbcon_release(struct fb_info *info)
if (info->fbcon_par) {
struct fbcon_par *par = info->fbcon_par;
- fbcon_del_cursor_work(info);
+ fbcon_del_cursor_work_sync(info);
kfree(par->cursor_state.mask);
kfree(par->cursor_data);
kfree(par->cursor_src);
diff --git a/drivers/video/fbdev/core/fbcon.h b/drivers/video/fbdev/core/fbcon.h
index d93a89877d0433..6a2f7f6e5a8c32 100644
--- a/drivers/video/fbdev/core/fbcon.h
+++ b/drivers/video/fbdev/core/fbcon.h
@@ -97,6 +97,7 @@ struct fbcon_par {
int blank_state;
int graphics;
bool initialized;
+ bool cursor_blink_on;
int rotate;
char *cursor_data;
#ifdef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION
|
| 53/3 | 2026/10/27 11:08 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 3190 output: 38 thoughts: 418 Thoughts: **KMSAN Fuzzing Session Feasibility Assessment** Okay, let's take a look at this patch and decide if it's worth throwing a KMSAN fuzzing session at it. The changes are focused in `drivers/video/fbdev/core/fbcon.c` and `drivers/video/fbdev/core/fbcon.h`, so it's a bit focused. First, a quick overview of what's been changed: 1. In `struct fbcon_par`, a `bool cursor_blink_on;` has been added. That's immediately interesting, it could lead to all sorts of concurrency issues if not handled right. 2. `fb_flashcursor()` now has a check for `!par->cursor_blink_on` and moves `console_unlock()` to after `queue_delayed_work(...)`. The comment is a pretty big clue as to what's going on; looks like they're trying to prevent a race condition with `fbcon_del_cursor_work()`. This locking change is a prime candidate for concurrency bugs. 3. `fbcon_add_cursor_work()` now has a check for `fbcon_cursor_blink`, which means the functionality can be turned off. It also sets `par->cursor_blink_on = true` and queues a delayed work. 4. `fbcon_del_cursor_work()` sets `par->cursor_blink_on = false` and cancels the delayed work. Pretty standard. 5. There's a new function, `fbcon_del_cursor_work_sync(struct fb_info *info)`, that just calls `cancel_delayed_work_sync(&par->cursor_work)`. Syncing it is a good idea. 6. Finally, `fbcon_release()` now uses the synced version of cursor deletion. This suggests there might be a lifecycle issue here and needs a synchronization. Now, I need to understand the lifecycle of `struct fbcon_par`. I need to figure out where it's allocated, initialized, and freed because I want to understand potential use-after-free and double-free vulnerabilities. Time to use my grepper or `read-file` to check `fbcon.c` and figure out where this struct comes from and where it goes. This patch has good KMSAN candidate potential, so I want to be certain this patch doesn't introduce memory safety issues. |
| 54/3 | 2026/10/27 11:08 | tool | grepper |
0mArgs:{
"Expression": "fbcon_par",
"PathPrefixes": [
"drivers/video/fbdev/core/fbcon.c"
]
}Results: {
"Output": "\nFull output is too long, showing 200 out of 303 lines.\nUse more precise expression or PathPrefixes if possible.\n\nNumber of matching lines per file (1 files in total):\ndrivers/video/fbdev/core/fbcon.c:59\n\ndrivers/video/fbdev/core/fbcon.c=200=static inline void fbcon_set_rotation(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-201-{\ndrivers/video/fbdev/core/fbcon.c:202:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-203-\n--\ndrivers/video/fbdev/core/fbcon.c=211=static void fbcon_rotate(struct fb_info *info, u32 rotate)\ndrivers/video/fbdev/core/fbcon.c-212-{\ndrivers/video/fbdev/core/fbcon.c:213:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-214-\tstruct fb_info *fb_info;\n--\ndrivers/video/fbdev/core/fbcon.c=233=static void fbcon_rotate_all(struct fb_info *info, u32 rotate)\ndrivers/video/fbdev/core/fbcon.c-234-{\ndrivers/video/fbdev/core/fbcon.c:235:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-236-\tstruct vc_data *vc;\n--\ndrivers/video/fbdev/core/fbcon.c=256=static inline void fbcon_set_rotation(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-257-{\ndrivers/video/fbdev/core/fbcon.c:258:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-259-\n--\ndrivers/video/fbdev/core/fbcon.c=268=static void fbcon_rotate_all(struct fb_info *info, u32 rotate)\n--\ndrivers/video/fbdev/core/fbcon.c-273-\ndrivers/video/fbdev/core/fbcon.c:274:static void fbcon_set_bitops(struct fbcon_par *par)\ndrivers/video/fbdev/core/fbcon.c-275-{\n--\ndrivers/video/fbdev/core/fbcon.c=294=static int fbcon_get_rotate(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-295-{\ndrivers/video/fbdev/core/fbcon.c:296:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-297-\n--\ndrivers/video/fbdev/core/fbcon.c=306=static inline bool fbcon_is_active(struct vc_data *vc, struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-307-{\ndrivers/video/fbdev/core/fbcon.c:308:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-309-\n--\ndrivers/video/fbdev/core/fbcon.c=391=static void fb_flashcursor(struct work_struct *work)\ndrivers/video/fbdev/core/fbcon.c-392-{\ndrivers/video/fbdev/core/fbcon.c:393:\tstruct fbcon_par *par = container_of(work, struct fbcon_par, cursor_work.work);\ndrivers/video/fbdev/core/fbcon.c-394-\tstruct fb_info *info;\n--\ndrivers/video/fbdev/core/fbcon.c=436=static void fbcon_add_cursor_work(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-437-{\ndrivers/video/fbdev/core/fbcon.c:438:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-439-\n--\ndrivers/video/fbdev/core/fbcon.c=457=static void fbcon_del_cursor_work(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-458-{\ndrivers/video/fbdev/core/fbcon.c:459:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-460-\n--\ndrivers/video/fbdev/core/fbcon.c=469=static void fbcon_del_cursor_work_sync(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-470-{\ndrivers/video/fbdev/core/fbcon.c:471:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-472-\n--\ndrivers/video/fbdev/core/fbcon.c=646=static void fbcon_prepare_logo(struct vc_data *vc, struct fb_info *info,\n--\ndrivers/video/fbdev/core/fbcon.c-649-\t/* Need to make room for the logo */\ndrivers/video/fbdev/core/fbcon.c:650:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-651-\tint cnt, erase = vc-\u003evc_video_erase_char, step;\n--\ndrivers/video/fbdev/core/fbcon.c=743=static void set_blitting_type(struct vc_data *vc, struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-744-{\ndrivers/video/fbdev/core/fbcon.c:745:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-746-\n--\ndrivers/video/fbdev/core/fbcon.c=768=static void set_blitting_type(struct vc_data *vc, struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-769-{\ndrivers/video/fbdev/core/fbcon.c:770:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-771-\n--\ndrivers/video/fbdev/core/fbcon.c=785=static void fbcon_release(struct fb_info *info)\n--\ndrivers/video/fbdev/core/fbcon.c-793-\ndrivers/video/fbdev/core/fbcon.c:794:\tif (info-\u003efbcon_par) {\ndrivers/video/fbdev/core/fbcon.c:795:\t\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-796-\n--\ndrivers/video/fbdev/core/fbcon.c-803-#endif\ndrivers/video/fbdev/core/fbcon.c:804:\t\tkfree(info-\u003efbcon_par);\ndrivers/video/fbdev/core/fbcon.c:805:\t\tinfo-\u003efbcon_par = NULL;\ndrivers/video/fbdev/core/fbcon.c-806-\t}\n--\ndrivers/video/fbdev/core/fbcon.c=809=static int fbcon_open(struct fb_info *info)\ndrivers/video/fbdev/core/fbcon.c-810-{\ndrivers/video/fbdev/core/fbcon.c:811:\tstruct fbcon_par *par;\ndrivers/video/fbdev/core/fbcon.c-812-\n--\ndrivers/video/fbdev/core/fbcon.c-832-\tpar-\u003einfo = info;\ndrivers/video/fbdev/core/fbcon.c:833:\tinfo-\u003efbcon_par = par;\ndrivers/video/fbdev/core/fbcon.c-834-\tpar-\u003ecur_blink_jiffies = HZ / 5;\n--\ndrivers/video/fbdev/core/fbcon.c=878=static void con2fb_init_display(struct vc_data *vc, struct fb_info *info,\n--\ndrivers/video/fbdev/core/fbcon.c-880-{\ndrivers/video/fbdev/core/fbcon.c:881:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-882-\tint ret;\n--\ndrivers/video/fbdev/core/fbcon.c=1026=static const char *fbcon_startup(void)\n--\ndrivers/video/fbdev/core/fbcon.c-1032-\tstruct fb_info *info = NULL;\ndrivers/video/fbdev/core/fbcon.c:1033:\tstruct fbcon_par *par;\ndrivers/video/fbdev/core/fbcon.c-1034-\tint rows, cols;\n--\ndrivers/video/fbdev/core/fbcon.c-1052-\ndrivers/video/fbdev/core/fbcon.c:1053:\tpar = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1054-\tpar-\u003ecurrcon = -1;\n--\ndrivers/video/fbdev/core/fbcon.c=1100=static void fbcon_init(struct vc_data *vc, bool init)\n--\ndrivers/video/fbdev/core/fbcon.c-1102-\tstruct fb_info *info;\ndrivers/video/fbdev/core/fbcon.c:1103:\tstruct fbcon_par *par;\ndrivers/video/fbdev/core/fbcon.c-1104-\tstruct vc_data **default_mode = vc-\u003evc_display_fg;\n--\ndrivers/video/fbdev/core/fbcon.c-1127-\ndrivers/video/fbdev/core/fbcon.c:1128:\tif (!info-\u003efbcon_par)\ndrivers/video/fbdev/core/fbcon.c-1129-\t\tif (con2fb_acquire_newinfo(vc, info, vc-\u003evc_num))\n--\ndrivers/video/fbdev/core/fbcon.c-1178-\ndrivers/video/fbdev/core/fbcon.c:1179:\tpar = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1180-\tpar-\u003ecur_blink_jiffies = msecs_to_jiffies(vc-\u003evc_cur_blink_ms);\n--\ndrivers/video/fbdev/core/fbcon.c=1280=static void fbcon_deinit(struct vc_data *vc)\n--\ndrivers/video/fbdev/core/fbcon.c-1283-\tstruct fb_info *info;\ndrivers/video/fbdev/core/fbcon.c:1284:\tstruct fbcon_par *par;\ndrivers/video/fbdev/core/fbcon.c-1285-\tint idx;\n--\ndrivers/video/fbdev/core/fbcon.c-1298-\ndrivers/video/fbdev/core/fbcon.c:1299:\tpar = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1300-\n--\ndrivers/video/fbdev/core/fbcon.c=1350=static void __fbcon_clear(struct vc_data *vc, unsigned int sy, unsigned int sx,\n--\ndrivers/video/fbdev/core/fbcon.c-1353-\tstruct fb_info *info = fbcon_info_from_console(vc-\u003evc_num);\ndrivers/video/fbdev/core/fbcon.c:1354:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1355-\tint fg, bg;\n--\ndrivers/video/fbdev/core/fbcon.c=1396=static void fbcon_putcs(struct vc_data *vc, const u16 *s, unsigned int count,\n--\ndrivers/video/fbdev/core/fbcon.c-1400-\tstruct fbcon_display *p = \u0026fb_display[vc-\u003evc_num];\ndrivers/video/fbdev/core/fbcon.c:1401:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1402-\n--\ndrivers/video/fbdev/core/fbcon.c=1409=static void fbcon_clear_margins(struct vc_data *vc, int bottom_only)\n--\ndrivers/video/fbdev/core/fbcon.c-1411-\tstruct fb_info *info = fbcon_info_from_console(vc-\u003evc_num);\ndrivers/video/fbdev/core/fbcon.c:1412:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1413-\n--\ndrivers/video/fbdev/core/fbcon.c=1418=static void fbcon_cursor(struct vc_data *vc, bool enable)\n--\ndrivers/video/fbdev/core/fbcon.c-1420-\tstruct fb_info *info = fbcon_info_from_console(vc-\u003evc_num);\ndrivers/video/fbdev/core/fbcon.c:1421:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1422- \tint c = scr_readw((u16 *) vc-\u003evc_pos);\n--\ndrivers/video/fbdev/core/fbcon.c=1448=static void fbcon_set_disp(struct fb_info *info, struct fb_var_screeninfo *var,\n--\ndrivers/video/fbdev/core/fbcon.c-1453-\tstruct vc_data *svc;\ndrivers/video/fbdev/core/fbcon.c:1454:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1455-\tint rows, cols, ret;\n--\ndrivers/video/fbdev/core/fbcon.c=1511=static __inline__ void ywrap_up(struct vc_data *vc, int count)\n--\ndrivers/video/fbdev/core/fbcon.c-1513-\tstruct fb_info *info = fbcon_info_from_console(vc-\u003evc_num);\ndrivers/video/fbdev/core/fbcon.c:1514:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1515-\tstruct fbcon_display *p = \u0026fb_display[vc-\u003evc_num];\n--\ndrivers/video/fbdev/core/fbcon.c=1530=static __inline__ void ywrap_down(struct vc_data *vc, int count)\n--\ndrivers/video/fbdev/core/fbcon.c-1532-\tstruct fb_info *info = fbcon_info_from_console(vc-\u003evc_num);\ndrivers/video/fbdev/core/fbcon.c:1533:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1534-\tstruct fbcon_display *p = \u0026fb_display[vc-\u003evc_num];\n--\ndrivers/video/fbdev/core/fbcon.c=1549=static __inline__ void ypan_up(struct vc_data *vc, int count)\n--\ndrivers/video/fbdev/core/fbcon.c-1552-\tstruct fbcon_display *p = \u0026fb_display[vc-\u003evc_num];\ndrivers/video/fbdev/core/fbcon.c:1553:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1554-\n--\ndrivers/video/fbdev/core/fbcon.c=1573=static __inline__ void ypan_up_redraw(struct vc_data *vc, int t, int count)\n--\ndrivers/video/fbdev/core/fbcon.c-1575-\tstruct fb_info *info = fbcon_info_from_console(vc-\u003evc_num);\ndrivers/video/fbdev/core/fbcon.c:1576:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1577-\tstruct fbcon_display *p = \u0026fb_display[vc-\u003evc_num];\n--\ndrivers/video/fbdev/core/fbcon.c=1597=static __inline__ void ypan_down(struct vc_data *vc, int count)\n--\ndrivers/video/fbdev/core/fbcon.c-1600-\tstruct fbcon_display *p = \u0026fb_display[vc-\u003evc_num];\ndrivers/video/fbdev/core/fbcon.c:1601:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1602-\n--\ndrivers/video/fbdev/core/fbcon.c=1621=static __inline__ void ypan_down_redraw(struct vc_data *vc, int t, int count)\n--\ndrivers/video/fbdev/core/fbcon.c-1623-\tstruct fb_info *info = fbcon_info_from_console(vc-\u003evc_num);\ndrivers/video/fbdev/core/fbcon.c:1624:\tstruct fbcon_par *par = info-\u003efbcon_par;\ndrivers/video/fbdev/core/fbcon.c-1625-\tstruct fbcon_display *p = \u0026fb_display[vc-\u003evc_num];\n--\ndrivers/video/fbdev/core/fbcon.c=1677=static void fbcon_redraw_blit(struct vc_data *vc, struct fb_info *info,\n\n"
} |
| 55/3 | 2026/10/27 11:08 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 8922 output: 41 thoughts: 25 Thoughts: Here's my take on the thought process, summarized as you requested: **Deconstructing fbcon_open and par Allocation** Okay, so I need to understand how this `par` variable is being allocated within `fbcon_open`. The best place to start, as I recall from my previous work with framebuffer consoles, is probably around line 810 where `fbcon_open` is defined. I'll need to carefully examine that section of the code and see exactly how the `par` variable is declared, initialized, and potentially reassigned within the function. My goal is to understand how the memory for `par` is managed and to spot any potential issues or nuances in its handling that might be relevant to the current problem I'm investigating. This is likely the crucial step to comprehending how resources are handled with regard to this variable. |
| 56/3 | 2026/10/27 11:08 | tool | read-file |
0mArgs:{
"File": "drivers/video/fbdev/core/fbcon.c",
"FirstLine": 808,
"LineCount": 40
}Results: {
"Contents": " 808:\t\n 809:\tstatic int fbcon_open(struct fb_info *info)\n 810:\t{\n 811:\t\tstruct fbcon_par *par;\n 812:\t\n 813:\t\tif (!try_module_get(info-\u003efbops-\u003eowner))\n 814:\t\t\treturn -ENODEV;\n 815:\t\n 816:\t\tlock_fb_info(info);\n 817:\t\tif (info-\u003efbops-\u003efb_open \u0026\u0026\n 818:\t\t info-\u003efbops-\u003efb_open(info, 0)) {\n 819:\t\t\tunlock_fb_info(info);\n 820:\t\t\tmodule_put(info-\u003efbops-\u003eowner);\n 821:\t\t\treturn -ENODEV;\n 822:\t\t}\n 823:\t\tunlock_fb_info(info);\n 824:\t\n 825:\t\tpar = kzalloc_obj(*par);\n 826:\t\tif (!par) {\n 827:\t\t\tfbcon_release(info);\n 828:\t\t\treturn -ENOMEM;\n 829:\t\t}\n 830:\t\n 831:\t\tINIT_DELAYED_WORK(\u0026par-\u003ecursor_work, fb_flashcursor);\n 832:\t\tpar-\u003einfo = info;\n 833:\t\tinfo-\u003efbcon_par = par;\n 834:\t\tpar-\u003ecur_blink_jiffies = HZ / 5;\n 835:\t\n 836:\t\treturn 0;\n 837:\t}\n 838:\t\n 839:\tstatic int con2fb_acquire_newinfo(struct vc_data *vc, struct fb_info *info,\n 840:\t\t\t\t\t int unit)\n 841:\t{\n 842:\t\tint err;\n 843:\t\n 844:\t\terr = fbcon_open(info);\n 845:\t\tif (err)\n 846:\t\t\treturn err;\n 847:\t\n"
} |
| 57/3 | 2026/10/27 11:08 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 9703 output: 41 thoughts: 335 Thoughts: **Analyzing the Cursor Blink Logic in fbcon.c** Alright, let's break down this cursor blink behavior. Looking at `fbcon_open`, the `par` structure, which is a `fbcon_par` object, is being allocated using `kzalloc_obj`. That's key; it means all the fields, including this new `cursor_blink_on` boolean I added, are guaranteed to be initialized to zero, or false in this case. Now, tracing the changes, `fbcon_add_cursor_work()` sets `par->cursor_blink_on` to true, activating the blink. Conversely, `fbcon_del_cursor_work()` sets it back to false, deactivating it. The interesting part is in `fb_flashcursor()`. The crucial conditional check `if (!par->cursor_blink_on || ...)` uses our new boolean. And now, the `queue_delayed_work()` call is safely inside the console lock's critical section. The real problem seems to have been in `fbcon_release()`. The old version called `fbcon_del_cursor_work(info)`, which only called `cancel_delayed_work()` on the cursor work. This was non-synchronous, which means that the work callback might re-queue itself or access `par` *after* it's been freed, leading to a nasty use-after-free or a race condition. Now, thankfully, the fix is in place. `fbcon_release()` now calls `fbcon_del_cursor_work_sync(info)`, which in turn calls `cancel_delayed_work_sync(&par->cursor_work);`. This is much better, as the sync version will wait for the work to be completed before freeing the `par` structure, and it seems to solve the race issue by ensuring that the cursor work is properly canceled *before* `par` is released. To get the full picture, let's double-check the code from lines 390 to 480 in `fbcon.c` to see the complete context. Gotta make sure nothing else is lurking in there! |
| 58/3 | 2026/10/27 11:08 | tool | read-file |
0mArgs:{
"File": "drivers/video/fbdev/core/fbcon.c",
"FirstLine": 390,
"LineCount": 90
}Results: {
"Contents": " 390:\t\n 391:\tstatic void fb_flashcursor(struct work_struct *work)\n 392:\t{\n 393:\t\tstruct fbcon_par *par = container_of(work, struct fbcon_par, cursor_work.work);\n 394:\t\tstruct fb_info *info;\n 395:\t\tstruct vc_data *vc = NULL;\n 396:\t\tint c;\n 397:\t\tbool enable;\n 398:\t\tint ret;\n 399:\t\n 400:\t\t/* FIXME: we should sort out the unbind locking instead */\n 401:\t\t/* instead we just fail to flash the cursor if we can't get\n 402:\t\t * the lock instead of blocking fbcon deinit */\n 403:\t\tret = console_trylock();\n 404:\t\tif (ret == 0)\n 405:\t\t\treturn;\n 406:\t\n 407:\t\t/* protected by console_lock */\n 408:\t\tinfo = par-\u003einfo;\n 409:\t\n 410:\t\tif (par-\u003ecurrcon != -1)\n 411:\t\t\tvc = vc_cons[par-\u003ecurrcon].d;\n 412:\t\n 413:\t\tif (!par-\u003ecursor_blink_on ||\n 414:\t\t !vc || !con_is_visible(vc) ||\n 415:\t\t fbcon_info_from_console(vc-\u003evc_num) != info ||\n 416:\t\t vc-\u003evc_deccm != 1) {\n 417:\t\t\tconsole_unlock();\n 418:\t\t\treturn;\n 419:\t\t}\n 420:\t\n 421:\t\tc = scr_readw((u16 *) vc-\u003evc_pos);\n 422:\t\tenable = par-\u003ecursor_flash \u0026\u0026 !par-\u003ecursor_state.enable;\n 423:\t\tpar-\u003ebitops-\u003ecursor(vc, info, enable,\n 424:\t\t\t\t get_fg_color(vc, info, c),\n 425:\t\t\t\t get_bg_color(vc, info, c));\n 426:\t\n 427:\t\t/*\n 428:\t\t * Re-arm under console_lock so that a concurrent\n 429:\t\t * fbcon_del_cursor_work() cannot race with this requeue.\n 430:\t\t */\n 431:\t\tqueue_delayed_work(system_power_efficient_wq, \u0026par-\u003ecursor_work,\n 432:\t\t\t\t par-\u003ecur_blink_jiffies);\n 433:\t\tconsole_unlock();\n 434:\t}\n 435:\t\n 436:\tstatic void fbcon_add_cursor_work(struct fb_info *info)\n 437:\t{\n 438:\t\tstruct fbcon_par *par = info-\u003efbcon_par;\n 439:\t\n 440:\t\tif (!fbcon_cursor_blink)\n 441:\t\t\treturn;\n 442:\t\n 443:\t\tpar-\u003ecursor_blink_on = true;\n 444:\t\tqueue_delayed_work(system_power_efficient_wq, \u0026par-\u003ecursor_work,\n 445:\t\t\t\t par-\u003ecur_blink_jiffies);\n 446:\t}\n 447:\t\n 448:\t/*\n 449:\t * Stop the cursor blink.\n 450:\t *\n 451:\t * Does not wait for a callback that is already running, so it is safe to\n 452:\t * call from any context.\n 453:\t *\n 454:\t * console_lock serializes this with the requeue in fb_flashcursor();\n 455:\t * otherwise a running callback could re-arm the work.\n 456:\t */\n 457:\tstatic void fbcon_del_cursor_work(struct fb_info *info)\n 458:\t{\n 459:\t\tstruct fbcon_par *par = info-\u003efbcon_par;\n 460:\t\n 461:\t\tpar-\u003ecursor_blink_on = false;\n 462:\t\tcancel_delayed_work(\u0026par-\u003ecursor_work);\n 463:\t}\n 464:\t\n 465:\t/*\n 466:\t * Stop the cursor blink and wait for a running callback to finish before\n 467:\t * @par is freed. May sleep, only for teardown paths.\n 468:\t */\n 469:\tstatic void fbcon_del_cursor_work_sync(struct fb_info *info)\n 470:\t{\n 471:\t\tstruct fbcon_par *par = info-\u003efbcon_par;\n 472:\t\n 473:\t\tcancel_delayed_work_sync(\u0026par-\u003ecursor_work);\n 474:\t}\n 475:\t\n 476:\tunsigned char *fbcon_cursor_glyph(const struct vc_font *font, unsigned int cursor_type)\n 477:\t{\n 478:\t\tunsigned int height = font-\u003eheight;\n 479:\t\tunsigned int cursor_size = vc_cursor_valid_size(CUR_SIZE(cursor_type));\n"
} |
| 59/3 | 2026/10/27 11:08 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 11890 output: 269 thoughts: 794 Thoughts: **Analyzing a Kernel Bug Fix: Concurrency, Use-After-Free, and KMSAN Implications** Okay, let's break down this bug fix. My initial thought is to understand the problem. It seems there's a race condition in the framebuffer console driver, specifically around cursor handling. The previous code had `fbcon_release()` calling `fbcon_del_cursor_work()`, which ultimately used `cancel_delayed_work()`. However, if `fb_flashcursor` was running on another CPU, `cancel_delayed_work()` wouldn't wait for it to complete. Then, `fbcon_release()` would go ahead and free crucial cursor-related memory (`mask`, `data`, `src`, and finally `fbcon_par`). Meanwhile, `fb_flashcursor`, after calling `console_unlock()`, would re-arm the workqueue with `queue_delayed_work(...)`. This meant the workqueue was re-arming after the resources it needed had been freed, a classic use-after-free scenario. This is definitely a concurrency issue. Now, my next question is whether this fix introduces any new risks, specifically related to uninitialized memory. Let's see... I've got to review the four criteria for `NeedsKMSAN=true`. First, is kernel data being leaked to user space? Nope, no copy-to-user, put_user, netlink, ioctls, or anything like that. Second, are we relying on uninitialized variables in any conditional logic? The patch does add a `cursor_blink_on` field to `struct fbcon_par`. However, `fbcon_par` is allocated using `kzalloc_obj`, which *zeroes* this new field, so it's initialized. It also explicitly gets set, so it's all good. Third, are we allocating complex structures and potentially reading uninitialized fields later? Doesn't look like it. Finally, are we messing with bounds checks, lengths, or anything that could create a window to read uninitialized memory? No. Alright, so I'm thinking KMSAN isn't needed here. But, just to be absolutely sure, let's consider the protections in place and what could be missing. KASAN is the right tool to catch memory access violations like use-after-free, which is precisely the problem here. This bug involves a race between work execution and cleanup, leading to UAF, which is exactly the kind of bug KASAN detects. KMSAN detects uninitialized reads/leaks to user space. The patch modifies cursor work synchronization by adding a flag, using the console lock, and using `cancel_delayed_work_sync`. Crucially, `kzalloc_obj` initializes all the memory for the blink flag so uninitialized data is not present. There are no user-space copies, no uninitialized buffers, and no length changes. Thus, there are no uninitialized memory risks added or exposed. Therefore, KMSAN is not needed here. Okay, I'm confident in this analysis. Time to set the results. |
| 60/3 | 2026/10/27 11:09 | tool | set-results |
0mArgs:{
"KMSANReasoning": "The patch addresses a concurrency/race condition bug in fbcon's delayed cursor blink work where fb_flashcursor could race with fbcon_del_cursor_work/fbcon_release, potentially leading to use-after-free or improper re-arming of work during teardown.\n\nKASAN vs KMSAN applicability:\n- KASAN is designed to detect use-after-free and out-of-bounds memory accesses. The lifecycle and synchronization issues around `cursor_work` and `struct fbcon_par` tearing down are squarely within KASAN's domain.\n- KMSAN detects reads of uninitialized memory and information leaks to userspace. The patch adds a single boolean field `cursor_blink_on` to `struct fbcon_par`, which is allocated with `kzalloc_obj` (ensuring it is zero-initialized), and alters delayed work cancellation and requeue locking. No data is copied to userspace, no uninitialized memory is read or exposed, and no buffer sizes or bounds are affected.\n\nBecause the changes do not introduce or expose any uninitialized memory hazards, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
}Results: {
"KMSANReasoning": "The patch addresses a concurrency/race condition bug in fbcon's delayed cursor blink work where fb_flashcursor could race with fbcon_del_cursor_work/fbcon_release, potentially leading to use-after-free or improper re-arming of work during teardown.\n\nKASAN vs KMSAN applicability:\n- KASAN is designed to detect use-after-free and out-of-bounds memory accesses. The lifecycle and synchronization issues around `cursor_work` and `struct fbcon_par` tearing down are squarely within KASAN's domain.\n- KMSAN detects reads of uninitialized memory and information leaks to userspace. The patch adds a single boolean field `cursor_blink_on` to `struct fbcon_par`, which is allocated with `kzalloc_obj` (ensuring it is zero-initialized), and alters delayed work cancellation and requeue locking. No data is copied to userspace, no uninitialized memory is read or exposed, and no buffer sizes or bounds are affected.\n\nBecause the changes do not introduce or expose any uninitialized memory hazards, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
} |
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| Total Calls | Total Duration (Seconds) | Avg Duration (Seconds) |
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