AI Trajectory

null

{
  "EnableConfigs": [
    "BLK_DEV_NULL_BLK",
    "BLK_DEV_MD"
  ],
  "FocusSymbols": [
    "_badblocks_set",
    "_badblocks_clear",
    "badblocks_check"
  ],
  "Reasoning": "The patch fixes an overflow issue and incorrect usage of rounddown/roundup macros in the badblocks block layer API. The badblocks API is reachable via sysfs and configfs (e.g., null_blk, md), making it functional and testable.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit c4edb6b4d610a8fb829bdb3fcaf3ba960bc86864\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Sat Jul 4 18:16:31 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/block/badblocks.c b/block/badblocks.c\nindex ece64e76fe8fff..e848491253235f 100644\n--- a/block/badblocks.c\n+++ b/block/badblocks.c\n@@ -853,15 +853,21 @@ static bool _badblocks_set(struct badblocks *bb, sector_t s, sector_t sectors,\n \t\t/* Invalid sectors number */\n \t\treturn false;\n \n+\tif (s \u003e ULLONG_MAX - sectors)\n+\t\treturn false;\n+\n \tif (bb-\u003eshift) {\n \t\t/* round the start down, and the end up */\n \t\tsector_t next = s + sectors;\n \n-\t\trounddown(s, 1 \u003c\u003c bb-\u003eshift);\n-\t\troundup(next, 1 \u003c\u003c bb-\u003eshift);\n+\t\ts = round_down(s, 1 \u003c\u003c bb-\u003eshift);\n+\t\tnext = round_up(next, 1 \u003c\u003c bb-\u003eshift);\n \t\tsectors = next - s;\n \t}\n \n+\tif (sectors == 0)\n+\t\treturn false;\n+\n \twrite_seqlock_irqsave(\u0026bb-\u003elock, flags);\n \n \tbad.ack = acknowledged;\n@@ -1061,6 +1067,9 @@ static bool _badblocks_clear(struct badblocks *bb, sector_t s, sector_t sectors)\n \t\t/* Invalid sectors number */\n \t\treturn false;\n \n+\tif (s \u003e ULLONG_MAX - sectors)\n+\t\treturn false;\n+\n \tif (bb-\u003eshift) {\n \t\tsector_t target;\n \n@@ -1071,11 +1080,17 @@ static bool _badblocks_clear(struct badblocks *bb, sector_t s, sector_t sectors)\n \t\t * isn't than to think a block is not bad when it is.\n \t\t */\n \t\ttarget = s + sectors;\n-\t\troundup(s, 1 \u003c\u003c bb-\u003eshift);\n-\t\trounddown(target, 1 \u003c\u003c bb-\u003eshift);\n-\t\tsectors = target - s;\n+\t\ts = round_up(s, 1 \u003c\u003c bb-\u003eshift);\n+\t\ttarget = round_down(target, 1 \u003c\u003c bb-\u003eshift);\n+\t\tif (target \u003c s)\n+\t\t\tsectors = 0;\n+\t\telse\n+\t\t\tsectors = target - s;\n \t}\n \n+\tif (sectors == 0)\n+\t\treturn false;\n+\n \twrite_seqlock_irq(\u0026bb-\u003elock);\n \n \tbad.ack = true;\n@@ -1303,13 +1318,22 @@ int badblocks_check(struct badblocks *bb, sector_t s, sector_t sectors,\n \n \tWARN_ON(bb-\u003eshift \u003c 0 || sectors == 0);\n \n+\tif (s \u003e ULLONG_MAX - sectors)\n+\t\treturn -EINVAL;\n+\n \tif (bb-\u003eshift \u003e 0) {\n \t\t/* round the start down, and the end up */\n \t\tsector_t target = s + sectors;\n \n-\t\trounddown(s, 1 \u003c\u003c bb-\u003eshift);\n-\t\troundup(target, 1 \u003c\u003c bb-\u003eshift);\n-\t\tsectors = target - s;\n+\t\ts = round_down(s, 1 \u003c\u003c bb-\u003eshift);\n+\t\ttarget = round_up(target, 1 \u003c\u003c bb-\u003eshift);\n+\t\tif (target \u003c s)\n+\t\t\tsectors = 0;\n+\t\telse\n+\t\t\tsectors = target - s;\n+\n+\t\tif (sectors == 0)\n+\t\t\treturn 0;\n \t}\n \n retry:\n"
}

gemini-3.1-pro-preview

null

{
  "EnableConfigs": [
    "BLK_DEV_NULL_BLK",
    "BLK_DEV_MD"
  ],
  "FocusSymbols": [
    "_badblocks_set",
    "_badblocks_clear",
    "badblocks_check"
  ],
  "Reasoning": "The patch fixes an overflow issue and incorrect usage of rounddown/roundup macros in the badblocks block layer API. The badblocks API is reachable via sysfs and configfs (e.g., null_blk, md), making it functional and testable.",
  "WorthFuzzing": true
}

You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).

If it modifies reachable core kernel logic, drivers, or architectures, use your code search
tools to verify the code can be executed, then return WorthFuzzing=true.

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Do not list too generic configs (we already have them enabled). Only list those that
   specifically cover the modified code. List them in the EnableConfigs output array,
   and DO NOT add a '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.

For your convenience, here is the diff of the changes:
commit c4edb6b4d610a8fb829bdb3fcaf3ba960bc86864
Author: syz-cluster <triage@syzkaller.com>
Date:   Sat Jul 4 18:16:31 2026 +0000

    syz-cluster: applied patch under review

diff --git a/block/badblocks.c b/block/badblocks.c
index ece64e76fe8fff..e848491253235f 100644
--- a/block/badblocks.c
+++ b/block/badblocks.c
@@ -853,15 +853,21 @@ static bool _badblocks_set(struct badblocks *bb, sector_t s, sector_t sectors,
 		/* Invalid sectors number */
 		return false;
 
+	if (s > ULLONG_MAX - sectors)
+		return false;
+
 	if (bb->shift) {
 		/* round the start down, and the end up */
 		sector_t next = s + sectors;
 
-		rounddown(s, 1 << bb->shift);
-		roundup(next, 1 << bb->shift);
+		s = round_down(s, 1 << bb->shift);
+		next = round_up(next, 1 << bb->shift);
 		sectors = next - s;
 	}
 
+	if (sectors == 0)
+		return false;
+
 	write_seqlock_irqsave(&bb->lock, flags);
 
 	bad.ack = acknowledged;
@@ -1061,6 +1067,9 @@ static bool _badblocks_clear(struct badblocks *bb, sector_t s, sector_t sectors)
 		/* Invalid sectors number */
 		return false;
 
+	if (s > ULLONG_MAX - sectors)
+		return false;
+
 	if (bb->shift) {
 		sector_t target;
 
@@ -1071,11 +1080,17 @@ static bool _badblocks_clear(struct badblocks *bb, sector_t s, sector_t sectors)
 		 * isn't than to think a block is not bad when it is.
 		 */
 		target = s + sectors;
-		roundup(s, 1 << bb->shift);
-		rounddown(target, 1 << bb->shift);
-		sectors = target - s;
+		s = round_up(s, 1 << bb->shift);
+		target = round_down(target, 1 << bb->shift);
+		if (target < s)
+			sectors = 0;
+		else
+			sectors = target - s;
 	}
 
+	if (sectors == 0)
+		return false;
+
 	write_seqlock_irq(&bb->lock);
 
 	bad.ack = true;
@@ -1303,13 +1318,22 @@ int badblocks_check(struct badblocks *bb, sector_t s, sector_t sectors,
 
 	WARN_ON(bb->shift < 0 || sectors == 0);
 
+	if (s > ULLONG_MAX - sectors)
+		return -EINVAL;
+
 	if (bb->shift > 0) {
 		/* round the start down, and the end up */
 		sector_t target = s + sectors;
 
-		rounddown(s, 1 << bb->shift);
-		roundup(target, 1 << bb->shift);
-		sectors = target - s;
+		s = round_down(s, 1 << bb->shift);
+		target = round_up(target, 1 << bb->shift);
+		if (target < s)
+			sectors = 0;
+		else
+			sectors = target - s;
+
+		if (sectors == 0)
+			return 0;
 	}
 
 retry:

gemini-3.1-pro-preview

null

null

							input: 2533
							output: 18
							thoughts: 175
						

**Analyzing the Badblocks Patch**

Okay, so this patch is aimed at `block/badblocks.c`. My initial read shows it's addressing potential integer overflows within the bad block management code. Specifically, the functions `_badblocks_set`, `_badblocks_clear`, and `badblocks_check` are getting some overflow checks added. Good, defensive programming is always a win in critical kernel subsystems like this.

And now, I see it's also fixing the usage of `rounddown` and `roundup`. Hmm, that seems odd at first glance. I immediately thought, "Aren't those macros?" And if I recall correctly, they should return the rounded value, but they shouldn't modify the input variable in place. So, why is the patch changing how they're used? Replacing `s = rounddown(s, ...)` with `s = round_down(s, ...)` makes it sound like they were trying to modify the variable directly.

Alright, time to go deeper. Let's confirm my suspicions. I'll quickly check the kernel's `rounddown` and `roundup` definitions. Ah, yes, they're defined in `include/linux/math.h`. Let's confirm the definitions and usage in the kernel code using grepper, just to be thorough and verify my expectations. I can quickly understand the rationale behind the patch this way.

{
  "Expression": "#define rounddown"
}

{
  "Output": "include/linux/log2.h=65=unsigned long __rounddown_pow_of_two(unsigned long n)\n--\ninclude/linux/log2.h-190- */\ninclude/linux/log2.h:191:#define rounddown_pow_of_two(n)\t\t\t\\\ninclude/linux/log2.h-192-(\t\t\t\t\t\t\\\n--\ninclude/linux/math.h-84- */\ninclude/linux/math.h:85:#define rounddown(x, y) (\t\t\t\t\\\ninclude/linux/math.h-86-{\t\t\t\t\t\t\t\\\n--\ntools/include/linux/log2.h=56=unsigned long __rounddown_pow_of_two(unsigned long n)\n--\ntools/include/linux/log2.h-167- */\ntools/include/linux/log2.h:168:#define rounddown_pow_of_two(n)\t\t\t\\\ntools/include/linux/log2.h-169-(\t\t\t\t\t\t\\\n"
}

gemini-3.1-pro-preview

null

null

							input: 3277
							output: 18
							thoughts: 154
						

**Fixing the `rounddown()` Bug in `badblocks.c`**

Okay, so looking at this code snippet, I see the issue immediately. The original code in `block/badblocks.c` was calling `rounddown(s, 1 << bb->shift)` and `roundup(next, 1 << bb->shift)` without actually assigning the return value. That's a classic mistake! These functions, as I recall, are meant to *return* the rounded value; they don't operate *in place*. So, the variables `s` and `next` were never actually being modified as intended.

The fix, as the patch demonstrates, is straightforward: the corrected code now correctly assigns the result of the rounding functions back to the original variables: `s = round_down(s, 1 << bb->shift);` and `next = round_up(next, 1 << bb->shift);`. This ensures the subsequent logic operates on the rounded values, which is the whole point.

This is a functional change, not just a cosmetic one. Since this fix is in the block layer, I should dig deeper to understand which configuration options trigger the `badblocks` functionality. It would be helpful to determine the specific scenarios this impacts.

{
  "Expression": "badblocks.o"
}

{
  "Output": "block/Makefile=8=obj-y\t\t:= bdev.o fops.o bio.o elevator.o blk-core.o blk-sysfs.o \\\n--\nblock/Makefile-12-\t\t\tblk-mq-sysfs.o blk-mq-cpumap.o blk-mq-sched.o ioctl.o \\\nblock/Makefile:13:\t\t\tgenhd.o ioprio.o badblocks.o partitions/ blk-rq-qos.o \\\nblock/Makefile-14-\t\t\tdisk-events.o blk-ia-ranges.o early-lookup.o\n--\ndrivers/block/null_blk/main.c=475=NULLB_DEVICE_ATTR(rotational, bool, NULL);\ndrivers/block/null_blk/main.c:476:NULLB_DEVICE_ATTR(badblocks_once, bool, NULL);\ndrivers/block/null_blk/main.c-477-NULLB_DEVICE_ATTR(badblocks_partial_io, bool, NULL);\n--\ndrivers/block/null_blk/main.c=596=static struct configfs_attribute *nullb_device_attrs[] = {\ndrivers/block/null_blk/main.c-597-\t\u0026nullb_device_attr_badblocks,\ndrivers/block/null_blk/main.c:598:\t\u0026nullb_device_attr_badblocks_once,\ndrivers/block/null_blk/main.c-599-\t\u0026nullb_device_attr_badblocks_partial_io,\n--\ndrivers/block/null_blk/main.c=1346=blk_status_t null_handle_badblocks(struct nullb_cmd *cmd, sector_t sector,\n--\ndrivers/block/null_blk/main.c-1357-\ndrivers/block/null_blk/main.c:1358:\tif (cmd-\u003enq-\u003edev-\u003ebadblocks_once)\ndrivers/block/null_blk/main.c-1359-\t\tbadblocks_clear(bb, first_bad, bad_sectors);\n--\ndrivers/block/null_blk/null_blk.h=53=struct nullb_device {\n--\ndrivers/block/null_blk/null_blk.h-65-\tstruct badblocks badblocks;\ndrivers/block/null_blk/null_blk.h:66:\tbool badblocks_once;\ndrivers/block/null_blk/null_blk.h-67-\tbool badblocks_partial_io;\n--\ndrivers/md/raid1-10.c=278=static inline bool raid1_should_read_first(struct mddev *mddev,\n--\ndrivers/md/raid1-10.c-293- * bio with REQ_RAHEAD or REQ_NOWAIT can fail at anytime, before such IO is\ndrivers/md/raid1-10.c:294: * submitted to the underlying disks, hence don't record badblocks or retry\ndrivers/md/raid1-10.c-295- * in this case.\n"
}

gemini-3.1-pro-preview

null

null

							input: 4470
							output: 22
							thoughts: 39
						

**Analyzing the Block Device Build Process**

Okay, so I'm looking at this `badblocks.o` file and it seems like it's being included in the kernel build. The location of it, `block/Makefile`, with `obj-y` implies it's always compiled in. But hold on, let me double-check that `block/Makefile` just to be certain. I need to be absolutely sure about the build configuration and dependency chain here before I make any assumptions. Best to verify the specifics.

no matches

{
  "Expression": "obj-y.*badblocks.o"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 4655
							output: 18
							thoughts: 299
						

**Analyzing the Badblocks Implementation**

Okay, so I'm looking at the `block/Makefile`. Line 13, in particular, seems important. It's buried within a multi-line `obj-y` assignment, which is usually a sign that this code is compiled in statically, assuming `CONFIG_BLOCK` is enabled. And, as I recall, `CONFIG_BLOCK` is essentially a default in most modern kernels. That tells me that this `badblocks.o` file is likely always part of the build, unless someone explicitly disabled the block device support.

Now, let's get into the specifics of what's been changed within the file itself. Specifically, I need to know the functions that are modified. Based on the file, the functions affected are `_badblocks_set`, `_badblocks_clear`, and `badblocks_check`. All of these are part of the core badblocks API. My next question is: who uses them? I need to know where these functions are called from to determine the scope of impact for this particular change.

{
  "Expression": "badblocks_set"
}

{
  "Output": "block/badblocks.c-22- *\nblock/badblocks.c:23: * When the caller of badblocks_set() wants to set a range of bad blocks, the\nblock/badblocks.c-24- * setting range can be acked or unacked. And the setting range may merge,\n--\nblock/badblocks.c-320- * the bad block range setting conditions. Maybe there is some rare corner case\nblock/badblocks.c:321: * is not considered and optimized, it won't hurt if badblocks_set() fails due\nblock/badblocks.c-322- * to no space, or some ranges are not merged to save bad blocks table space.\nblock/badblocks.c-323- *\nblock/badblocks.c:324: * Inside badblocks_set() each loop starts by jumping to re_insert label, every\nblock/badblocks.c-325- * time for the new loop prev_badblocks() is called to find an already set range\n--\nblock/badblocks.c=817=static bool try_adjacent_combine(struct badblocks *bb, int prev)\n--\nblock/badblocks.c-838-/* Do exact work to set bad block range into the bad block table */\nblock/badblocks.c:839:static bool _badblocks_set(struct badblocks *bb, sector_t s, sector_t sectors,\nblock/badblocks.c-840-\t\t\t   int acknowledged)\n--\nblock/badblocks.c=1347=EXPORT_SYMBOL_GPL(badblocks_check);\n--\nblock/badblocks.c-1349-/**\nblock/badblocks.c:1350: * badblocks_set() - Add a range of bad blocks to the table.\nblock/badblocks.c-1351- * @bb:\t\tthe badblocks structure that holds all badblock information\n--\nblock/badblocks.c-1364- */\nblock/badblocks.c:1365:bool badblocks_set(struct badblocks *bb, sector_t s, sector_t sectors,\nblock/badblocks.c-1366-\t\t   int acknowledged)\nblock/badblocks.c-1367-{\nblock/badblocks.c:1368:\treturn _badblocks_set(bb, s, sectors, acknowledged);\nblock/badblocks.c-1369-}\nblock/badblocks.c:1370:EXPORT_SYMBOL_GPL(badblocks_set);\nblock/badblocks.c-1371-\n--\nblock/badblocks.c=1488=ssize_t badblocks_store(struct badblocks *bb, const char *page, size_t len,\n--\nblock/badblocks.c-1507-\nblock/badblocks.c:1508:\tif (!badblocks_set(bb, sector, length, !unack))\nblock/badblocks.c-1509-\t\treturn -ENOSPC;\n--\ndrivers/block/null_blk/main.c=532=static ssize_t nullb_device_badblocks_store(struct config_item *item,\n--\ndrivers/block/null_blk/main.c-564-\tif (buf[0] == '+') {\ndrivers/block/null_blk/main.c:565:\t\tif (badblocks_set(\u0026t_dev-\u003ebadblocks, start,\ndrivers/block/null_blk/main.c-566-\t\t\t\t  end - start + 1, 1))\n--\ndrivers/md/md.c=1808=static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)\n--\ndrivers/md/md.c-1931-\t\t\t\tbreak;\ndrivers/md/md.c:1932:\t\t\tif (!badblocks_set(\u0026rdev-\u003ebadblocks, sector, count, 1))\ndrivers/md/md.c-1933-\t\t\t\treturn -EINVAL;\n--\ndrivers/md/md.c=10556=bool rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,\n--\ndrivers/md/md.c-10575-\ndrivers/md/md.c:10576:\tif (!badblocks_set(\u0026rdev-\u003ebadblocks, s, sectors, 0)) {\ndrivers/md/md.c-10577-\t\t/*\n--\ndrivers/nvdimm/badrange.c=165=static void set_badblock(struct badblocks *bb, sector_t s, int num)\n--\ndrivers/nvdimm/badrange.c-169-\t/* this isn't an error as the hardware will still throw an exception */\ndrivers/nvdimm/badrange.c:170:\tif (!badblocks_set(bb, s, num, 1))\ndrivers/nvdimm/badrange.c-171-\t\tdev_info_once(bb-\u003edev, \"%s: failed for sector %llx\\n\",\n--\ninclude/linux/badblocks.h=51=int badblocks_check(struct badblocks *bb, sector_t s, sector_t sectors,\ninclude/linux/badblocks.h-52-\t\t    sector_t *first_bad, sector_t *bad_sectors);\ninclude/linux/badblocks.h:53:bool badblocks_set(struct badblocks *bb, sector_t s, sector_t sectors,\ninclude/linux/badblocks.h-54-\t\t   int acknowledged);\n"
}

gemini-3.1-pro-preview

null

null

							input: 6565
							output: 18
							thoughts: 79
						

Okay, let's break this down.

**Investigating the `badblocks` Interface in the Kernel**

Right, so I'm seeing that the `badblocks_set` function is called by a few key drivers: the `null_blk` driver, the software RAID component (`md`), and the `nvdimm` driver. That's a reasonable set of users. These are all places where bad block management would be relevant – virtual block devices, RAID configurations, and non-volatile memory devices.

Then, I'm also observing that `badblocks_store` is invoked through sysfs. That suggests some user-space interaction, a way for an administrator or tool to directly manage bad block information. But this raises a question: is `badblocks_store` being *exported* for use by `md` or `null_blk`, or is it just being called independently through sysfs in those contexts? I need to clarify that relationship. Let me just quickly trace through `badblocks_store` and get a clearer picture of how it's used and what it does in relation to the drivers that are calling `badblocks_set`.

{
  "Expression": "badblocks_store"
}

{
  "Output": "block/badblocks.c=1476=EXPORT_SYMBOL_GPL(badblocks_show);\n--\nblock/badblocks.c-1478-/**\nblock/badblocks.c:1479: * badblocks_store() - sysfs access to bad-blocks list\nblock/badblocks.c-1480- * @bb:\t\tthe badblocks structure that holds all badblock information\n--\nblock/badblocks.c-1487- */\nblock/badblocks.c:1488:ssize_t badblocks_store(struct badblocks *bb, const char *page, size_t len,\nblock/badblocks.c-1489-\t\t\tint unack)\n--\nblock/badblocks.c-1512-}\nblock/badblocks.c:1513:EXPORT_SYMBOL_GPL(badblocks_store);\nblock/badblocks.c-1514-\n--\nblock/genhd.c=851=static ssize_t disk_badblocks_show(struct device *dev,\n--\nblock/genhd.c-862-\nblock/genhd.c:863:static ssize_t disk_badblocks_store(struct device *dev,\nblock/genhd.c-864-\t\t\t\t\tstruct device_attribute *attr,\n--\nblock/genhd.c-871-\nblock/genhd.c:872:\treturn badblocks_store(disk-\u003ebb, page, len, 0);\nblock/genhd.c-873-}\n--\nblock/genhd.c=1172=static DEVICE_ATTR(inflight, 0444, part_inflight_show, NULL);\nblock/genhd.c:1173:static DEVICE_ATTR(badblocks, 0644, disk_badblocks_show, disk_badblocks_store);\nblock/genhd.c-1174-static DEVICE_ATTR(diskseq, 0444, diskseq_show, NULL);\n--\ndrivers/block/null_blk/main.c=525=static ssize_t nullb_device_badblocks_show(struct config_item *item, char *page)\n--\ndrivers/block/null_blk/main.c-531-\ndrivers/block/null_blk/main.c:532:static ssize_t nullb_device_badblocks_store(struct config_item *item,\ndrivers/block/null_blk/main.c-533-\t\t\t\t     const char *page, size_t count)\n--\ndrivers/md/md.c=3612=static ssize_t bb_store(struct md_rdev *rdev, const char *page, size_t len)\ndrivers/md/md.c-3613-{\ndrivers/md/md.c:3614:\tint rv = badblocks_store(\u0026rdev-\u003ebadblocks, page, len, 0);\ndrivers/md/md.c-3615-\t/* Maybe that ack was all we needed */\n--\ndrivers/md/md.c=3627=static ssize_t ubb_store(struct md_rdev *rdev, const char *page, size_t len)\ndrivers/md/md.c-3628-{\ndrivers/md/md.c:3629:\treturn badblocks_store(\u0026rdev-\u003ebadblocks, page, len, 1);\ndrivers/md/md.c-3630-}\n--\ninclude/linux/badblocks.h=57=ssize_t badblocks_show(struct badblocks *bb, char *page, int unack);\ninclude/linux/badblocks.h:58:ssize_t badblocks_store(struct badblocks *bb, const char *page, size_t len,\ninclude/linux/badblocks.h-59-\t\t\tint unack);\n"
}

gemini-3.1-pro-preview

null

null

							input: 7846
							output: 18
							thoughts: 127
						

**Fuzzing Block Devices via sysfs: A Potentially Interesting Vector**

Okay, so I'm looking at how bad block handling is implemented and I see that `badblocks_store` is used by `disk_badblocks_store` within `block/genhd.c`. That's interesting, and it immediately clicks that this means any block device with badblocks enabled potentially has a sysfs interface for fuzzing! This warrants immediate attention.

Let me confirm the access method. Alright, `disk_badblocks_store` is registered with `DEVICE_ATTR(badblocks, 0644, disk_badblocks_show, disk_badblocks_store)`. That placement in sysfs is going to make it accessible through `/sys/block/<dev>/badblocks`. Yup, that's definitely reachable and a completely functional entrypoint. This is definitely something that is worth a deeper investigation.

Okay, I'm going to shift gears and check `badblocks_check` as well, since that's another important function related to the badblocks feature.

{
  "Expression": "badblocks_check"
}

{
  "Output": "block/badblocks.c-282- *     blocks table are all acked, merging them into a larger one range may\nblock/badblocks.c:283: *     occupy less bad blocks table space and make badblocks_check() faster.\nblock/badblocks.c-284- *     Therefore in such situation, after overwriting range S, the previous range\n--\nblock/badblocks.c=1055=static bool _badblocks_clear(struct badblocks *bb, sector_t s, sector_t sectors)\n--\nblock/badblocks.c-1200-/* Do the exact work to check bad blocks range from the bad block table */\nblock/badblocks.c:1201:static int _badblocks_check(struct badblocks *bb, sector_t s, sector_t sectors,\nblock/badblocks.c-1202-\t\t\t    sector_t *first_bad, sector_t *bad_sectors)\n--\nblock/badblocks.c-1279-/**\nblock/badblocks.c:1280: * badblocks_check() - check a given range for bad sectors\nblock/badblocks.c-1281- * @bb:\t\tthe badblocks structure that holds all badblock information\n--\nblock/badblocks.c-1295- *\nblock/badblocks.c:1296: * Locking of the bad-block table uses a seqlock so badblocks_check\nblock/badblocks.c-1297- * might need to retry if it is very unlucky.\n--\nblock/badblocks.c-1312- */\nblock/badblocks.c:1313:int badblocks_check(struct badblocks *bb, sector_t s, sector_t sectors,\nblock/badblocks.c-1314-\t\t\tsector_t *first_bad, sector_t *bad_sectors)\n--\nblock/badblocks.c-1340-\tseq = read_seqbegin(\u0026bb-\u003elock);\nblock/badblocks.c:1341:\trv = _badblocks_check(bb, s, sectors, first_bad, bad_sectors);\nblock/badblocks.c-1342-\tif (read_seqretry(\u0026bb-\u003elock, seq))\n--\nblock/badblocks.c-1346-}\nblock/badblocks.c:1347:EXPORT_SYMBOL_GPL(badblocks_check);\nblock/badblocks.c-1348-\n--\ndrivers/block/null_blk/main.c=1346=blk_status_t null_handle_badblocks(struct nullb_cmd *cmd, sector_t sector,\n--\ndrivers/block/null_blk/main.c-1354-\ndrivers/block/null_blk/main.c:1355:\tif (!badblocks_check(bb, sector, *nr_sectors, \u0026first_bad, \u0026bad_sectors))\ndrivers/block/null_blk/main.c-1356-\t\treturn BLK_STS_OK;\n--\ndrivers/md/md.h=299=static inline int is_badblock(struct md_rdev *rdev, sector_t s, sector_t sectors,\n--\ndrivers/md/md.h-302-\tif (unlikely(rdev-\u003ebadblocks.count)) {\ndrivers/md/md.h:303:\t\tint rv = badblocks_check(\u0026rdev-\u003ebadblocks, rdev-\u003edata_offset + s,\ndrivers/md/md.h-304-\t\t\t\t\tsectors,\n--\ndrivers/nvdimm/nd.h=676=static inline bool is_bad_pmem(struct badblocks *bb, sector_t sector,\n--\ndrivers/nvdimm/nd.h-682-\ndrivers/nvdimm/nd.h:683:\t\treturn !!badblocks_check(bb, sector, len / 512, \u0026first_bad,\ndrivers/nvdimm/nd.h-684-\t\t\t\t\u0026num_bad);\n--\ndrivers/nvdimm/pfn_devs.c=353=static int nd_pfn_clear_memmap_errors(struct nd_pfn *nd_pfn)\n--\ndrivers/nvdimm/pfn_devs.c-383-\ndrivers/nvdimm/pfn_devs.c:384:\t\tbb_present = badblocks_check(\u0026nd_region-\u003ebb, meta_start,\ndrivers/nvdimm/pfn_devs.c-385-\t\t\t\tmeta_num, \u0026first_bad, \u0026num_bad);\n--\ndrivers/nvdimm/pmem.c=242=__weak long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,\n--\ndrivers/nvdimm/pmem.c-258-\tif (bb-\u003ecount \u0026\u0026\ndrivers/nvdimm/pmem.c:259:\t    badblocks_check(bb, sector, num, \u0026first_bad, \u0026num_bad)) {\ndrivers/nvdimm/pmem.c-260-\t\tlong actual_nr;\n--\ninclude/linux/badblocks.h=45=struct badblocks_context {\n--\ninclude/linux/badblocks.h-50-\ninclude/linux/badblocks.h:51:int badblocks_check(struct badblocks *bb, sector_t s, sector_t sectors,\ninclude/linux/badblocks.h-52-\t\t    sector_t *first_bad, sector_t *bad_sectors);\n"
}

gemini-3.1-pro-preview

null

null

							input: 9575
							output: 17
							thoughts: 60
						

**Fuzzing the `badblocks_check` Functionality**

Okay, so I see that `badblocks_check` is utilized by a few key components: `null_blk`, `md`, and `nvdimm`. Given that list, `null_blk` immediately stands out as a prime candidate for fuzzing. It feels like a relatively contained and accessible target within that group. My next step will be to quickly determine if `null_blk` is enabled by default in a typical configuration, or if I need to enable it with specific kernel configuration options before I can even start testing the `badblocks_check` behavior within that module. Identifying any dependencies or required configuration will be essential before I can get to the good stuff.

{
  "Expression": "null_blk"
}

{
  "Output": "Documentation/block/blk-mq.rst=139=Further reading\n--\nDocumentation/block/blk-mq.rst-145-\nDocumentation/block/blk-mq.rst:146:- `Null block device driver \u003chttps://www.kernel.org/doc/html/latest/block/null_blk.html\u003e`_\nDocumentation/block/blk-mq.rst-147-\n--\nDocumentation/block/index.rst=4=Block\n--\nDocumentation/block/index.rst-18-   kyber-iosched\nDocumentation/block/index.rst:19:   null_blk\nDocumentation/block/index.rst-20-   pr\n--\nDocumentation/block/null_blk.rst=83=discard=[0/1]: Default: 0\nDocumentation/block/null_blk.rst:84:  Support discard operations (requires memory-backed null_blk device).\nDocumentation/block/null_blk.rst-85-\n--\nDocumentation/block/null_blk.rst=118=blocking=[0/1]: Default: 0\n--\nDocumentation/block/null_blk.rst-122-  0  Register as a non-blocking blk-mq driver device.\nDocumentation/block/null_blk.rst:123:  1  Register as a blocking blk-mq driver device, null_blk will set\nDocumentation/block/null_blk.rst-124-     the BLK_MQ_F_BLOCKING flag, indicating that it sometimes/always\n--\nDocumentation/filesystems/zonefs.rst=400=zonefs-tools also includes a test suite which can be run against any zoned\nDocumentation/filesystems/zonefs.rst:401:block device, including null_blk block device created with zoned mode.\nDocumentation/filesystems/zonefs.rst-402-\n--\nDocumentation/nvme/nvme-pci-endpoint-target.rst=152=To facilitate testing, enabling the null-blk driver (CONFIG_BLK_DEV_NULL_BLK)\nDocumentation/nvme/nvme-pci-endpoint-target.rst:153:is also recommended. With this, a simple setup using a null_blk block device\nDocumentation/nvme/nvme-pci-endpoint-target.rst-154-as a subsystem namespace can be used.\n--\nDocumentation/nvme/nvme-pci-endpoint-target.rst=188=scope of this document. The following only provides a simple example of a port\nDocumentation/nvme/nvme-pci-endpoint-target.rst:189:and subsystem with a single namespace backed by a null_blk device.\nDocumentation/nvme/nvme-pci-endpoint-target.rst-190-\nDocumentation/nvme/nvme-pci-endpoint-target.rst=191=First, make sure that configfs is enabled::\n--\nDocumentation/nvme/nvme-pci-endpoint-target.rst-194-\nDocumentation/nvme/nvme-pci-endpoint-target.rst:195:Next, create a null_blk device (default settings give a 250 GB device without\nDocumentation/nvme/nvme-pci-endpoint-target.rst-196-memory backing). The block device created will be /dev/nullb0 by default::\nDocumentation/nvme/nvme-pci-endpoint-target.rst-197-\nDocumentation/nvme/nvme-pci-endpoint-target.rst:198:        # modprobe null_blk\nDocumentation/nvme/nvme-pci-endpoint-target.rst-199-        # ls /dev/nullb0\n--\nDocumentation/nvme/nvme-pci-endpoint-target.rst=212=example, the port is created with a maximum of 4 I/O queue pairs::\n--\nDocumentation/nvme/nvme-pci-endpoint-target.rst-221-\nDocumentation/nvme/nvme-pci-endpoint-target.rst:222:Next, create and enable the subsystem namespace using the null_blk block\nDocumentation/nvme/nvme-pci-endpoint-target.rst-223-device::\n--\nDocumentation/nvme/nvme-pci-endpoint-target.rst=285=target device and endpoint device are created and connected.\n--\nDocumentation/nvme/nvme-pci-endpoint-target.rst-288-\nDocumentation/nvme/nvme-pci-endpoint-target.rst:289:        null_blk: disk nullb0 created\nDocumentation/nvme/nvme-pci-endpoint-target.rst:290:        null_blk: module loaded\nDocumentation/nvme/nvme-pci-endpoint-target.rst-291-        nvmet: adding nsid 1 to subsystem nvmepf.0.nqn\n--\nDocumentation/translations/zh_CN/block/blk-mq.rst=112=I/O 请求完成了。\n--\nDocumentation/translations/zh_CN/block/blk-mq.rst-120-\nDocumentation/translations/zh_CN/block/blk-mq.rst:121:- `Null 块设备驱动程序 \u003chttps://www.kernel.org/doc/html/latest/block/null_blk.html\u003e`_\nDocumentation/translations/zh_CN/block/blk-mq.rst-122-\n--\nDocumentation/translations/zh_CN/block/index.rst=22=TODOList:\n--\nDocumentation/translations/zh_CN/block/index.rst-29-* kyber-iosched\nDocumentation/translations/zh_CN/block/index.rst:30:* null_blk\nDocumentation/translations/zh_CN/block/index.rst-31-* pr\n--\ndrivers/block/Kconfig=17=if BLK_DEV\ndrivers/block/Kconfig-18-\ndrivers/block/Kconfig:19:source \"drivers/block/null_blk/Kconfig\"\ndrivers/block/Kconfig-20-source \"drivers/block/rnull/Kconfig\"\n--\ndrivers/block/Makefile=35=obj-$(CONFIG_BLK_DEV_RNBD)\t+= rnbd/\ndrivers/block/Makefile-36-\ndrivers/block/Makefile:37:obj-$(CONFIG_BLK_DEV_NULL_BLK)\t+= null_blk/\ndrivers/block/Makefile-38-obj-$(CONFIG_BLK_DEV_RUST_NULL) += rnull/\n--\ndrivers/block/null_blk/Makefile=4=ccflags-y\t\t\t+= -I$(src)\ndrivers/block/null_blk/Makefile-5-\ndrivers/block/null_blk/Makefile:6:obj-$(CONFIG_BLK_DEV_NULL_BLK)\t+= null_blk.o\ndrivers/block/null_blk/Makefile:7:null_blk-objs\t\t\t:= main.o\ndrivers/block/null_blk/Makefile-8-ifeq ($(CONFIG_BLK_DEV_ZONED), y)\ndrivers/block/null_blk/Makefile:9:null_blk-$(CONFIG_TRACING) \t+= trace.o\ndrivers/block/null_blk/Makefile-10-endif\ndrivers/block/null_blk/Makefile:11:null_blk-$(CONFIG_BLK_DEV_ZONED) += zoned.o\n--\ndrivers/block/null_blk/main.c-11-#include \u003clinux/init.h\u003e\ndrivers/block/null_blk/main.c:12:#include \"null_blk.h\"\ndrivers/block/null_blk/main.c-13-\ndrivers/block/null_blk/main.c-14-#undef pr_fmt\ndrivers/block/null_blk/main.c:15:#define pr_fmt(fmt)\t\"null_blk: \" fmt\ndrivers/block/null_blk/main.c-16-\n--\ndrivers/block/null_blk/main.c=221=module_param_named(discard, g_discard, bool, 0444);\ndrivers/block/null_blk/main.c:222:MODULE_PARM_DESC(discard, \"Support discard operations (requires memory-backed null_blk device). Default: false\");\ndrivers/block/null_blk/main.c-223-\n--\ndrivers/block/null_blk/main.c=719=static ssize_t memb_group_features_show(struct config_item *item, char *page)\n--\ndrivers/block/null_blk/main.c-733-\t\tif (ret \u003e= left) {\ndrivers/block/null_blk/main.c:734:\t\t\tWARN_ONCE(1, \"Too many null_blk features to print\\n\");\ndrivers/block/null_blk/main.c-735-\t\t\tmemzero_explicit(page, PAGE_SIZE);\n--\ndrivers/block/null_blk/main.c=1395=static inline void nullb_complete_cmd(struct nullb_cmd *cmd)\n--\ndrivers/block/null_blk/main.c-1399-\t/*\ndrivers/block/null_blk/main.c:1400:\t * Since root privileges are required to configure the null_blk\ndrivers/block/null_blk/main.c-1401-\t * driver, it is fine that this driver does not initialize the\n--\ndrivers/block/null_blk/main.c-1403-\t * anyway if KMSAN is enabled to prevent that KMSAN complains\ndrivers/block/null_blk/main.c:1404:\t * about null_blk not initializing read data buffers.\ndrivers/block/null_blk/main.c-1405-\t */\n--\ndrivers/block/null_blk/trace.c-2-/*\ndrivers/block/null_blk/trace.c:3: * null_blk trace related helpers.\ndrivers/block/null_blk/trace.c-4- *\n--\ndrivers/block/null_blk/trace.c-9-/*\ndrivers/block/null_blk/trace.c:10: * Helper to use for all null_blk traces to extract disk name.\ndrivers/block/null_blk/trace.c-11- */\n--\ndrivers/block/null_blk/trace.h-2-/*\ndrivers/block/null_blk/trace.h:3: * null_blk device driver tracepoints.\ndrivers/block/null_blk/trace.h-4- *\n--\ndrivers/block/null_blk/trace.h-16-\ndrivers/block/null_blk/trace.h:17:#include \"null_blk.h\"\ndrivers/block/null_blk/trace.h-18-\n--\ndrivers/block/null_blk/zoned.c-3-#include \u003clinux/bitmap.h\u003e\ndrivers/block/null_blk/zoned.c:4:#include \"null_blk.h\"\ndrivers/block/null_blk/zoned.c-5-\n--\ndrivers/block/null_blk/zoned.c-9-#undef pr_fmt\ndrivers/block/null_blk/zoned.c:10:#define pr_fmt(fmt)\t\"null_blk: \" fmt\ndrivers/block/null_blk/zoned.c-11-\n--\ndrivers/block/null_blk/zoned.c=778=ssize_t zone_cond_store(struct nullb_device *dev, const char *page,\n--\ndrivers/block/null_blk/zoned.c-785-\tif (!dev-\u003ezoned) {\ndrivers/block/null_blk/zoned.c:786:\t\tpr_err(\"null_blk device is not zoned\\n\");\ndrivers/block/null_blk/zoned.c-787-\t\treturn -EINVAL;\n--\ndrivers/block/null_blk/zoned.c-790-\tif (!dev-\u003ezones) {\ndrivers/block/null_blk/zoned.c:791:\t\tpr_err(\"null_blk device is not yet powered\\n\");\ndrivers/block/null_blk/zoned.c-792-\t\treturn -EINVAL;\n--\ndrivers/block/rnull/configfs.rs=47=    fn make_group(\n--\ndrivers/block/rnull/configfs.rs-54-            attributes: [\ndrivers/block/rnull/configfs.rs:55:                // Named for compatibility with C null_blk\ndrivers/block/rnull/configfs.rs-56-                power: 0,\n--\ndrivers/block/rnull/rnull.rs=36=    fn init(_module: \u0026'static ThisModule) -\u003e impl PinInit\u003cSelf, Error\u003e {\ndrivers/block/rnull/rnull.rs:37:        pr_info!(\"Rust null_blk loaded\\n\");\ndrivers/block/rnull/rnull.rs-38-\n--\ndrivers/infiniband/ulp/rtrs/rtrs-clt.c=69=__rtrs_get_permit(struct rtrs_clt_sess *clt, enum rtrs_clt_con_type con_type)\n--\ndrivers/infiniband/ulp/rtrs/rtrs-clt.c-75-\t/*\ndrivers/infiniband/ulp/rtrs/rtrs-clt.c:76:\t * Adapted from null_blk get_tag(). Callers from different cpus may\ndrivers/infiniband/ulp/rtrs/rtrs-clt.c-77-\t * grab the same bit, since find_first_zero_bit is not atomic.\n--\nlib/fault-inject.c=267=EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);\n--\nlib/fault-inject.c-272-\nlib/fault-inject.c:273:/* These configfs attribute utilities are copied from drivers/block/null_blk/main.c */\nlib/fault-inject.c-274-\n"
}

gemini-3.1-pro-preview

null

null

							input: 13147
							output: 18
							thoughts: 497
						

**Fuzzing Target Identification: `badblocks` in Block Device Handling**

Okay, so I'm looking at how to best approach fuzzing the `badblocks` functionality, specifically with an eye towards the recently applied patch. The starting point here is the `CONFIG_BLK_DEV_NULL_BLK` configuration. Let's see if we need to explicitly enable it, I'll add `BLK_DEV_NULL_BLK` to `EnableConfigs` to be sure. However, the use of `null_blk` seems perfect for testing `badblocks` through configfs.

Now, considering the broader context, `CONFIG_MD` (Multiple Devices) is often enabled, and `drivers/md/md.c` calls `badblocks` functions, but `null_blk` is the clear easiest option here for testing badblocks through configfs.

The recent patch caught my eye, fixing an overflow issue in `_badblocks_set`, `_badblocks_clear`, and `badblocks_check` and also addressing `rounddown` and `roundup` macros within these functions. This is definitely a functional change and demands targeted fuzzing.

My primary focus then should be the specific functions touched by the patch. Let's see... Initially I was thinking of the main interface functions `badblocks_set`, `badblocks_clear`, `badblocks_check`, `badblocks_store`, and `badblocks_show`.

Ah, but the patch modified the internal functions, `_badblocks_set`, `_badblocks_clear` and `badblocks_check`. That's where I need to focus. `badblocks_check` should be listed, because it has been modified. So I'll list the key symbols as:

*   `_badblocks_set`
*   `_badblocks_clear`
*   `badblocks_check`
*   `badblocks_set`
*   `badblocks_clear`

Now I'll check `badblocks_clear` in `badblocks.c`.

{
  "Expression": "badblocks_clear"
}

{
  "Output": "block/badblocks.c=1037=static int front_splitting_clear(struct badblocks *bb, int prev,\n--\nblock/badblocks.c-1054-/* Do the exact work to clear bad block range from the bad block table */\nblock/badblocks.c:1055:static bool _badblocks_clear(struct badblocks *bb, sector_t s, sector_t sectors)\nblock/badblocks.c-1056-{\n--\nblock/badblocks.c=1370=EXPORT_SYMBOL_GPL(badblocks_set);\n--\nblock/badblocks.c-1372-/**\nblock/badblocks.c:1373: * badblocks_clear() - Remove a range of bad blocks to the table.\nblock/badblocks.c-1374- * @bb:\t\tthe badblocks structure that holds all badblock information\n--\nblock/badblocks.c-1385- */\nblock/badblocks.c:1386:bool badblocks_clear(struct badblocks *bb, sector_t s, sector_t sectors)\nblock/badblocks.c-1387-{\nblock/badblocks.c:1388:\treturn _badblocks_clear(bb, s, sectors);\nblock/badblocks.c-1389-}\nblock/badblocks.c:1390:EXPORT_SYMBOL_GPL(badblocks_clear);\nblock/badblocks.c-1391-\n--\ndrivers/block/null_blk/main.c=532=static ssize_t nullb_device_badblocks_store(struct config_item *item,\n--\ndrivers/block/null_blk/main.c-567-\t\t\tret = count;\ndrivers/block/null_blk/main.c:568:\t} else if (badblocks_clear(\u0026t_dev-\u003ebadblocks, start,\ndrivers/block/null_blk/main.c-569-\t\t\t\t   end - start + 1)) {\n--\ndrivers/block/null_blk/main.c=1346=blk_status_t null_handle_badblocks(struct nullb_cmd *cmd, sector_t sector,\n--\ndrivers/block/null_blk/main.c-1358-\tif (cmd-\u003enq-\u003edev-\u003ebadblocks_once)\ndrivers/block/null_blk/main.c:1359:\t\tbadblocks_clear(bb, first_bad, bad_sectors);\ndrivers/block/null_blk/main.c-1360-\n--\ndrivers/md/md.c=10596=void rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,\n--\ndrivers/md/md.c-10603-\ndrivers/md/md.c:10604:\tif (!badblocks_clear(\u0026rdev-\u003ebadblocks, s, sectors))\ndrivers/md/md.c-10605-\t\treturn;\n--\ndrivers/nvdimm/bus.c=164=static int nvdimm_clear_badblocks_region(struct device *dev, void *data)\n--\ndrivers/nvdimm/bus.c-183-\tsector = (ctx-\u003ephys - nd_region-\u003endr_start) / 512;\ndrivers/nvdimm/bus.c:184:\tbadblocks_clear(\u0026nd_region-\u003ebb, sector, ctx-\u003ecleared / 512);\ndrivers/nvdimm/bus.c-185-\n--\ndrivers/nvdimm/claim.c=233=static int nsio_rw_bytes(struct nd_namespace_common *ndns,\n--\ndrivers/nvdimm/claim.c-269-\t\t\t\tcleared /= 512;\ndrivers/nvdimm/claim.c:270:\t\t\t\tbadblocks_clear(\u0026nsio-\u003ebb, sector, cleared);\ndrivers/nvdimm/claim.c-271-\t\t\t}\n--\ndrivers/nvdimm/pmem.c=88=static void pmem_clear_bb(struct pmem_device *pmem, sector_t sector, long blks)\n--\ndrivers/nvdimm/pmem.c-91-\t\treturn;\ndrivers/nvdimm/pmem.c:92:\tbadblocks_clear(\u0026pmem-\u003ebb, sector, blks);\ndrivers/nvdimm/pmem.c-93-\tif (pmem-\u003ebb_state)\n--\ninclude/linux/badblocks.h=53=bool badblocks_set(struct badblocks *bb, sector_t s, sector_t sectors,\ninclude/linux/badblocks.h-54-\t\t   int acknowledged);\ninclude/linux/badblocks.h:55:bool badblocks_clear(struct badblocks *bb, sector_t s, sector_t sectors);\ninclude/linux/badblocks.h-56-void ack_all_badblocks(struct badblocks *bb);\n"
}

gemini-3.1-pro-preview

null

null

							input: 15314
							output: 20
							thoughts: 237
						

**Analyzing the Bad Block Handling Code**

Okay, let's get down to brass tacks. I'm looking at this patch and, initially, the key functions that have been directly altered appear to be `_badblocks_set`, `_badblocks_clear`, and `badblocks_check`.  I need to confirm this impression.

First, I had to clarify whether `badblocks_store` was modified, but it's not. Though it is important to note that it's called by `badblocks_set` and `badblocks_clear`. So, the patch seems to center around these three. I should focus my attention on these key functions.

Next, I needed to confirm that the `badblocks.c` module is, in fact, compiled by default. A quick check of the `block/Makefile` and the `obj-y` setting confirmed this.

Now, let me investigate the configuration aspects. I remember that `CONFIG_BLK_DEV_NULL_BLK` is beneficial, as it exposes badblocks through configfs. However, I need to make sure I'm considering all relevant locations.

Ah, there's another point. `badblocks_store` is also exposed through `disk_badblocks_store` within `block/genhd.c`. I'll need to remember to look at that function, as well.

{
  "Expression": "disk_badblocks_store"
}

{
  "Output": "block/genhd.c=851=static ssize_t disk_badblocks_show(struct device *dev,\n--\nblock/genhd.c-862-\nblock/genhd.c:863:static ssize_t disk_badblocks_store(struct device *dev,\nblock/genhd.c-864-\t\t\t\t\tstruct device_attribute *attr,\n--\nblock/genhd.c=1172=static DEVICE_ATTR(inflight, 0444, part_inflight_show, NULL);\nblock/genhd.c:1173:static DEVICE_ATTR(badblocks, 0644, disk_badblocks_show, disk_badblocks_store);\nblock/genhd.c-1174-static DEVICE_ATTR(diskseq, 0444, diskseq_show, NULL);\n"
}

gemini-3.1-pro-preview

null

null

							input: 16076
							output: 17
							thoughts: 42
						

Okay, let me think this through.

**Analyzing the `disk_badblocks` sysfs Attribute Implementation**

Alright, I'm tracing the implications here. It seems like any block device where the `disk->bb` structure is initialized is automatically going to have the sysfs attribute related to bad blocks functionality available. That's the core assumption, essentially tying the presence of that attribute directly to that `disk->bb` initialization.

Now, let's double-check how that's implemented. Ah, yes, looking at the code for the `disk_badblocks_store` function, it specifically checks if `disk->bb` is *not* NULL. That confirms the dependency I just hypothesized: if `disk->bb` is NULL, the functionality is disabled, and the sysfs attribute presumably won't even be created or will return an error when accessed. It is an important sanity check. So, that's the key requirement - initialization of `disk->bb`. Got it.

{
  "Expression": "disk-\u003ebb"
}

{
  "Output": "block/genhd.c=851=static ssize_t disk_badblocks_show(struct device *dev,\n--\nblock/genhd.c-856-\nblock/genhd.c:857:\tif (!disk-\u003ebb)\nblock/genhd.c-858-\t\treturn sysfs_emit(page, \"\\n\");\nblock/genhd.c-859-\nblock/genhd.c:860:\treturn badblocks_show(disk-\u003ebb, page, 0);\nblock/genhd.c-861-}\n--\nblock/genhd.c=863=static ssize_t disk_badblocks_store(struct device *dev,\n--\nblock/genhd.c-868-\nblock/genhd.c:869:\tif (!disk-\u003ebb)\nblock/genhd.c-870-\t\treturn -ENXIO;\nblock/genhd.c-871-\nblock/genhd.c:872:\treturn badblocks_store(disk-\u003ebb, page, len, 0);\nblock/genhd.c-873-}\n--\nblock/genhd.c=1236=static umode_t disk_visible(struct kobject *kobj, struct attribute *a, int n)\n--\nblock/genhd.c-1240-\nblock/genhd.c:1241:\tif (a == \u0026dev_attr_badblocks.attr \u0026\u0026 !disk-\u003ebb)\nblock/genhd.c-1242-\t\treturn 0;\n--\ndrivers/nvdimm/pmem.c=448=static int pmem_attach_disk(struct device *dev,\n--\ndrivers/nvdimm/pmem.c-553-\tnvdimm_badblocks_populate(nd_region, \u0026pmem-\u003ebb, \u0026bb_range);\ndrivers/nvdimm/pmem.c:554:\tdisk-\u003ebb = \u0026pmem-\u003ebb;\ndrivers/nvdimm/pmem.c-555-\n"
}

gemini-3.1-pro-preview

null

null

							input: 16852
							output: 16
							thoughts: 150
						

**My Configuration Consideration**

Okay, so I'm looking at this initialization of `disk->bb`. It seems like it's only done for `pmem`, or NVRAM. Hmm, what about `null_blk`? That module utilizes `t_dev->badblocks` but exposes it through configfs instead of sysfs. Right, and then I remember that `md` also handles badblocks, but exposes them differently. It uses `rdev->badblocks` and puts them in sysfs under `md/dev-xxx/bad_blocks`. This means that enabling both `CONFIG_BLK_DEV_NULL_BLK` and `CONFIG_MD` would be a good approach, I should add `BLK_DEV_NULL_BLK` and `MD` to `EnableConfigs` now.

Now I should just take a quick look at how `CONFIG_MD` is used.

{
  "Expression": "config MD"
}

{
  "Output": "drivers/clk/qcom/Kconfig=563=config MSM_LCC_8960\n--\ndrivers/clk/qcom/Kconfig-571-\ndrivers/clk/qcom/Kconfig:572:config MDM_GCC_9607\ndrivers/clk/qcom/Kconfig-573-\ttristate \"MDM9607 Global Clock Controller\"\n--\ndrivers/clk/qcom/Kconfig-579-\ndrivers/clk/qcom/Kconfig:580:config MDM_GCC_9615\ndrivers/clk/qcom/Kconfig-581-\ttristate \"MDM9615 Global Clock Controller\"\n--\ndrivers/md/Kconfig-5-\ndrivers/md/Kconfig:6:menuconfig MD\ndrivers/md/Kconfig-7-\tbool \"Multiple devices driver support (RAID and LVM)\"\n--\ndrivers/md/Kconfig=15=config BLK_DEV_MD\n--\ndrivers/md/Kconfig-39-\ndrivers/md/Kconfig:40:config MD_BITMAP\ndrivers/md/Kconfig-41-\tbool \"MD RAID bitmap support\"\n--\ndrivers/md/Kconfig-54-\ndrivers/md/Kconfig:55:config MD_LLBITMAP\ndrivers/md/Kconfig-56-\tbool \"MD RAID lockless bitmap support\"\n--\ndrivers/md/Kconfig-65-\ndrivers/md/Kconfig:66:config MD_AUTODETECT\ndrivers/md/Kconfig-67-\tbool \"Autodetect RAID arrays during kernel boot\"\n--\ndrivers/md/Kconfig-79-\ndrivers/md/Kconfig:80:config MD_BITMAP_FILE\ndrivers/md/Kconfig-81-\tbool \"MD bitmap file support (deprecated)\"\n--\ndrivers/md/Kconfig-90-\ndrivers/md/Kconfig:91:config MD_LINEAR\ndrivers/md/Kconfig-92-\ttristate \"Linear (append) mode\"\n--\ndrivers/md/Kconfig-103-\ndrivers/md/Kconfig:104:config MD_RAID0\ndrivers/md/Kconfig-105-\ttristate \"RAID-0 (striping) mode\"\n--\ndrivers/md/Kconfig-123-\ndrivers/md/Kconfig:124:config MD_RAID1\ndrivers/md/Kconfig-125-\ttristate \"RAID-1 (mirroring) mode\"\n--\ndrivers/md/Kconfig-145-\ndrivers/md/Kconfig:146:config MD_RAID10\ndrivers/md/Kconfig-147-\ttristate \"RAID-10 (mirrored striping) mode\"\n--\ndrivers/md/Kconfig-164-\ndrivers/md/Kconfig:165:config MD_RAID456\ndrivers/md/Kconfig-166-\ttristate \"RAID-4/RAID-5/RAID-6 mode\"\n--\ndrivers/md/Kconfig-201-\ndrivers/md/Kconfig:202:config MD_CLUSTER\ndrivers/md/Kconfig-203-\ttristate \"Cluster Support for MD\"\n--\ndrivers/net/ethernet/Kconfig=13=if ETHERNET\ndrivers/net/ethernet/Kconfig-14-\ndrivers/net/ethernet/Kconfig:15:config MDIO\ndrivers/net/ethernet/Kconfig-16-\ttristate\n--\ndrivers/net/mdio/Kconfig=19=config ACPI_MDIO\n--\ndrivers/net/mdio/Kconfig-23-\ndrivers/net/mdio/Kconfig:24:config MDIO_AIROHA\ndrivers/net/mdio/Kconfig-25-\ttristate \"Airoha AN7583 MDIO bus controller\"\n--\ndrivers/net/mdio/Kconfig-30-\ndrivers/net/mdio/Kconfig:31:config MDIO_SUN4I\ndrivers/net/mdio/Kconfig-32-\ttristate \"Allwinner sun4i MDIO interface support\"\n--\ndrivers/net/mdio/Kconfig-38-\ndrivers/net/mdio/Kconfig:39:config MDIO_XGENE\ndrivers/net/mdio/Kconfig-40-\ttristate \"APM X-Gene SoC MDIO bus controller\"\n--\ndrivers/net/mdio/Kconfig-45-\ndrivers/net/mdio/Kconfig:46:config MDIO_ASPEED\ndrivers/net/mdio/Kconfig-47-\ttristate \"ASPEED MDIO bus controller\"\n--\ndrivers/net/mdio/Kconfig-58-\ndrivers/net/mdio/Kconfig:59:config MDIO_BITBANG\ndrivers/net/mdio/Kconfig-60-\ttristate \"Bitbanged MDIO buses\"\n--\ndrivers/net/mdio/Kconfig-67-\ndrivers/net/mdio/Kconfig:68:config MDIO_BCM_IPROC\ndrivers/net/mdio/Kconfig-69-\ttristate \"Broadcom iProc MDIO bus controller\"\n--\ndrivers/net/mdio/Kconfig-76-\ndrivers/net/mdio/Kconfig:77:config MDIO_BCM_UNIMAC\ndrivers/net/mdio/Kconfig-78-\ttristate \"Broadcom UniMAC MDIO bus controller\"\n--\ndrivers/net/mdio/Kconfig-85-\ndrivers/net/mdio/Kconfig:86:config MDIO_CAVIUM\ndrivers/net/mdio/Kconfig-87-\ttristate\ndrivers/net/mdio/Kconfig-88-\ndrivers/net/mdio/Kconfig:89:config MDIO_GPIO\ndrivers/net/mdio/Kconfig-90-\ttristate \"GPIO lib-based bitbanged MDIO buses\"\n--\ndrivers/net/mdio/Kconfig-98-\ndrivers/net/mdio/Kconfig:99:config MDIO_HISI_FEMAC\ndrivers/net/mdio/Kconfig-100-\ttristate \"Hisilicon FEMAC MDIO bus controller\"\n--\ndrivers/net/mdio/Kconfig-105-\ndrivers/net/mdio/Kconfig:106:config MDIO_I2C\ndrivers/net/mdio/Kconfig-107-\ttristate\n--\ndrivers/net/mdio/Kconfig-115-\ndrivers/net/mdio/Kconfig:116:config MDIO_MVUSB\ndrivers/net/mdio/Kconfig-117-\ttristate \"Marvell USB to MDIO Adapter\"\n--\ndrivers/net/mdio/Kconfig-122-\ndrivers/net/mdio/Kconfig:123:config MDIO_MSCC_MIIM\ndrivers/net/mdio/Kconfig-124-\ttristate \"Microsemi MIIM interface support\"\n--\ndrivers/net/mdio/Kconfig-130-\ndrivers/net/mdio/Kconfig:131:config MDIO_MOXART\ndrivers/net/mdio/Kconfig-132-\ttristate \"MOXA ART MDIO interface support\"\n--\ndrivers/net/mdio/Kconfig-137-\ndrivers/net/mdio/Kconfig:138:config MDIO_OCTEON\ndrivers/net/mdio/Kconfig-139-\ttristate \"Octeon and some ThunderX SOCs MDIO buses\"\n--\ndrivers/net/mdio/Kconfig-147-\ndrivers/net/mdio/Kconfig:148:config MDIO_PIC64HPSC\ndrivers/net/mdio/Kconfig-149-\ttristate \"PIC64-HPSC/HX MDIO interface support\"\n--\ndrivers/net/mdio/Kconfig-155-\ndrivers/net/mdio/Kconfig:156:config MDIO_IPQ4019\ndrivers/net/mdio/Kconfig-157-\ttristate \"Qualcomm IPQ4019 MDIO interface support\"\n--\ndrivers/net/mdio/Kconfig-163-\ndrivers/net/mdio/Kconfig:164:config MDIO_IPQ8064\ndrivers/net/mdio/Kconfig-165-\ttristate \"Qualcomm IPQ8064 MDIO interface support\"\n--\ndrivers/net/mdio/Kconfig-171-\ndrivers/net/mdio/Kconfig:172:config MDIO_REALTEK_RTL9300\ndrivers/net/mdio/Kconfig-173-\ttristate \"Realtek RTL9300 MDIO interface support\"\n--\ndrivers/net/mdio/Kconfig-178-\ndrivers/net/mdio/Kconfig:179:config MDIO_REGMAP\ndrivers/net/mdio/Kconfig-180-\ttristate\n--\ndrivers/net/mdio/Kconfig-189-\ndrivers/net/mdio/Kconfig:190:config MDIO_THUNDER\ndrivers/net/mdio/Kconfig-191-\ttristate \"ThunderX SOCs MDIO buses\"\n--\ndrivers/net/mdio/Kconfig=200=comment \"MDIO Multiplexers\"\ndrivers/net/mdio/Kconfig-201-\ndrivers/net/mdio/Kconfig:202:config MDIO_BUS_MUX\ndrivers/net/mdio/Kconfig-203-\ttristate\n--\ndrivers/net/mdio/Kconfig-210-\ndrivers/net/mdio/Kconfig:211:config MDIO_BUS_MUX_MESON_G12A\ndrivers/net/mdio/Kconfig-212-\ttristate \"Amlogic G12a based MDIO bus multiplexer\"\n--\ndrivers/net/mdio/Kconfig-221-\ndrivers/net/mdio/Kconfig:222:config MDIO_BUS_MUX_MESON_GXL\ndrivers/net/mdio/Kconfig-223-\ttristate \"Amlogic GXL based MDIO bus multiplexer\"\n--\ndrivers/net/mdio/Kconfig-232-\ndrivers/net/mdio/Kconfig:233:config MDIO_BUS_MUX_BCM6368\ndrivers/net/mdio/Kconfig-234-\ttristate \"Broadcom BCM6368 MDIO bus multiplexers\"\n--\ndrivers/net/mdio/Kconfig-243-\ndrivers/net/mdio/Kconfig:244:config MDIO_BUS_MUX_BCM_IPROC\ndrivers/net/mdio/Kconfig-245-\ttristate \"Broadcom iProc based MDIO bus multiplexers\"\n--\ndrivers/net/mdio/Kconfig-254-\ndrivers/net/mdio/Kconfig:255:config MDIO_BUS_MUX_GPIO\ndrivers/net/mdio/Kconfig-256-\ttristate \"GPIO controlled MDIO bus multiplexers\"\n--\ndrivers/net/mdio/Kconfig-264-\ndrivers/net/mdio/Kconfig:265:config MDIO_BUS_MUX_MULTIPLEXER\ndrivers/net/mdio/Kconfig-266-\ttristate \"MDIO bus multiplexer using kernel multiplexer subsystem\"\n--\ndrivers/net/mdio/Kconfig-276-\ndrivers/net/mdio/Kconfig:277:config MDIO_BUS_MUX_MMIOREG\ndrivers/net/mdio/Kconfig-278-\ttristate \"MMIO device-controlled MDIO bus multiplexers\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 20121
							output: 124
							thoughts: 497
						

**Fuzzing Strategy Assessment**

Okay, so I'm looking at this patch and immediately, `CONFIG_BLK_DEV_MD` clicks – that's the MD config. I need to include `BLK_DEV_MD` and also `BLK_DEV_NULL_BLK`.

The patch itself is in `block/badblocks.c`, right? Right, and the reason for fuzzing is: it addresses an overflow and some incorrect macro usage related to `rounddown` and `roundup` in the badblocks block layer API. Good, that API is accessible through sysfs and configfs – thinking null_blk and md here – so it's actually testable. That's a huge plus.

Now, let's nail down the focus symbols. Looks like it's: `_badblocks_set`, `_badblocks_clear`, and `badblocks_check`. Yep, those make sense in the context of the described vulnerability. I'll definitely add those.

Just to be absolutely sure, I'm quickly confirming reachability of `badblocks_check`. It's called by `null_handle_badblocks` in `null_blk`, which is itself invoked on every IO if badblocks are configured. Perfect. `_badblocks_set` is called by `badblocks_set` which is called by `nullb_device_badblocks_store` in `null_blk` and `disk_badblocks_store` in `genhd.c` and `bb_store` in `md.c`. And `_badblocks_clear` is called by `badblocks_clear` which is called by `nullb_device_badblocks_store` and `null_handle_badblocks` and `rdev_clear_badblocks`.

So, yeah, the focus symbols are spot on. The config selections are correct for coverage. The reasoning makes total sense. All systems are go. I'm satisfied. Let's call set-results.

{
  "EnableConfigs": [
    "BLK_DEV_NULL_BLK",
    "BLK_DEV_MD"
  ],
  "FocusSymbols": [
    "_badblocks_set",
    "_badblocks_clear",
    "badblocks_check"
  ],
  "Reasoning": "The patch fixes an overflow issue and incorrect usage of rounddown/roundup macros in the badblocks block layer API. The badblocks API is reachable via sysfs and configfs (e.g., null_blk, md), making it functional and testable.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "BLK_DEV_NULL_BLK",
    "BLK_DEV_MD"
  ],
  "FocusSymbols": [
    "_badblocks_set",
    "_badblocks_clear",
    "badblocks_check"
  ],
  "Reasoning": "The patch fixes an overflow issue and incorrect usage of rounddown/roundup macros in the badblocks block layer API. The badblocks API is reachable via sysfs and configfs (e.g., null_blk, md), making it functional and testable.",
  "WorthFuzzing": true
}