AI Trajectory

null

{
  "EnableConfigs": [
    "EXT2_FS"
  ],
  "FocusSymbols": [
    "ext2_dio_write_iter",
    "ext2_file_write_iter"
  ],
  "KMSANReasoning": "The patch modifies scalar return value handling in ext2_dio_write_iter(): when a partial direct I/O write has already transferred some data (ret \u003e 0) and the subsequent buffered fallback write via generic_perform_write() fails (status \u003c 0), ret retains the number of bytes written rather than being overwritten with the negative error code.\n\nThis change does not allocate, initialize, read, or expose any kernel memory, nor does it copy uninitialized buffers or struct padding to userspace. All local variables involved (ret, status) are explicitly initialized. As there is no risk of uninitialized memory reads or information leaks, KMSAN is not applicable.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch modifies error return handling in ext2_dio_write_iter() when generic_perform_write() fails after a partial direct I/O write, preserving the number of bytes written instead of overwriting with the error code. ext2 is directly reachable in virtualized environments via loop devices and standard file write operations (such as open with O_DIRECT and write/pwritev).",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit 6a6988c4c560f62ce98dbf7ca377e9924a32bcab\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Mon Nov 2 11:12:34 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/fs/ext2/file.c b/fs/ext2/file.c\nindex 67fe423c3828d8..8ddc149d488481 100644\n--- a/fs/ext2/file.c\n+++ b/fs/ext2/file.c\n@@ -145,7 +145,8 @@ static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)\n \t\tpos = iocb-\u003eki_pos;\n \t\tstatus = generic_perform_write(iocb, from);\n \t\tif (unlikely(status \u003c 0)) {\n-\t\t\tret = status;\n+\t\t\tif (!ret)\n+\t\t\t\tret = status;\n \t\t\tgoto out_unlock;\n \t\t}\n \n"
}

core

null

{
  "EnableConfigs": [
    "EXT2_FS"
  ],
  "FocusSymbols": [
    "ext2_dio_write_iter",
    "ext2_file_write_iter"
  ],
  "Reasoning": "The patch modifies error return handling in ext2_dio_write_iter() when generic_perform_write() fails after a partial direct I/O write, preserving the number of bytes written instead of overwriting with the error code. ext2 is directly reachable in virtualized environments via loop devices and standard file write operations (such as open with O_DIRECT and write/pwritev).",
  "WorthFuzzing": true
}

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.

Target architecture: amd64

For your convenience, here is the diff of the changes:
commit 6a6988c4c560f62ce98dbf7ca377e9924a32bcab
Author: syz-cluster <triage@syzkaller.com>
Date:   Mon Nov 2 11:12:34 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index 67fe423c3828d8..8ddc149d488481 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -145,7 +145,8 @@ static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		pos = iocb->ki_pos;
 		status = generic_perform_write(iocb, from);
 		if (unlikely(status < 0)) {
-			ret = status;
+			if (!ret)
+				ret = status;
 			goto out_unlock;
 		}
 

gemini-3.8-flash

null

null

							input: 3006
							output: 37
							thoughts: 284
						

**Evaluating the Patch's Fuzzing Potential**

Okay, so the task is to determine if this patch justifies fuzzing with syzkaller. My initial instinct is to dive right in and dissect the changes. First things first, let's examine the commit diff itself. I need to understand exactly what code has been modified.

Alright, the diff points to `fs/ext2/file.c`. It looks like the change is within the `ext2_dio_write_iter` function, specifically around line 145. I can see a conditional block that's been altered. The original code unconditionally assigned the `status` to `ret` on error. Now, it only assigns the `status` if `ret` is still zero. This suggests a potential bug fix – the original code might have been overwriting a more significant error code. This is definitely worth a closer look.

I'll need to understand the surrounding context. Time to pull up the full file. I'll use `read-file` or `grepper` to get a better grasp of the code's behavior. I need to determine if this change introduces any new codepaths, error handling scenarios, or data flows that might be susceptible to fuzzing. I'll be looking for changes in error conditions, new branches, or any altered data flow that might lead to unexpected behavior when subjected to fuzzed inputs. It's too early to definitively say if fuzzing is necessary, but this warrants further scrutiny.

{
  "File": "fs/ext2/file.c",
  "FirstLine": 100,
  "LineCount": 100
}

{
  "Contents": " 100:\t\tssize_t ret;\n 101:\t\tunsigned int flags = 0;\n 102:\t\tunsigned long blocksize = inode-\u003ei_sb-\u003es_blocksize;\n 103:\t\tloff_t offset = iocb-\u003eki_pos;\n 104:\t\tloff_t count = iov_iter_count(from);\n 105:\t\tssize_t status = 0;\n 106:\t\n 107:\t\ttrace_ext2_dio_write_begin(iocb, from, 0);\n 108:\t\tinode_lock(inode);\n 109:\t\tret = generic_write_checks(iocb, from);\n 110:\t\tif (ret \u003c= 0)\n 111:\t\t\tgoto out_unlock;\n 112:\t\n 113:\t\tret = kiocb_modified(iocb);\n 114:\t\tif (ret)\n 115:\t\t\tgoto out_unlock;\n 116:\t\n 117:\t\t/* use IOMAP_DIO_FORCE_WAIT for unaligned or extending writes */\n 118:\t\tif (iocb-\u003eki_pos + iov_iter_count(from) \u003e i_size_read(inode) ||\n 119:\t\t   (!IS_ALIGNED(iocb-\u003eki_pos | iov_iter_alignment(from), blocksize)))\n 120:\t\t\tflags |= IOMAP_DIO_FORCE_WAIT;\n 121:\t\n 122:\t\tret = iomap_dio_rw(iocb, from, \u0026ext2_iomap_ops, \u0026ext2_dio_write_ops,\n 123:\t\t\t\t   flags, NULL, 0);\n 124:\t\n 125:\t\t/* ENOTBLK is magic return value for fallback to buffered-io */\n 126:\t\tif (ret == -ENOTBLK)\n 127:\t\t\tret = 0;\n 128:\t\n 129:\t\tif (ret \u003c 0 \u0026\u0026 ret != -EIOCBQUEUED)\n 130:\t\t\text2_write_failed(inode-\u003ei_mapping, offset + count);\n 131:\t\n 132:\t\t/* handle case for partial write and for fallback to buffered write */\n 133:\t\tif (ret \u003e= 0 \u0026\u0026 iov_iter_count(from)) {\n 134:\t\t\tloff_t pos, endbyte;\n 135:\t\t\tint ret2;\n 136:\t\n 137:\t\t\tiocb-\u003eki_flags \u0026= ~IOCB_DIRECT;\n 138:\t\n 139:\t\t\t/*\n 140:\t\t\t * Prevent concurrent direct I/O and buffered I/O to the same file\n 141:\t\t\t * range. Wait for in-flight DIO to finish before dirtying pages.\n 142:\t\t\t */\n 143:\t\t\tinode_dio_wait(inode);\n 144:\t\n 145:\t\t\tpos = iocb-\u003eki_pos;\n 146:\t\t\tstatus = generic_perform_write(iocb, from);\n 147:\t\t\tif (unlikely(status \u003c 0)) {\n 148:\t\t\t\tif (!ret)\n 149:\t\t\t\t\tret = status;\n 150:\t\t\t\tgoto out_unlock;\n 151:\t\t\t}\n 152:\t\n 153:\t\t\tret += status;\n 154:\t\t\tendbyte = pos + status - 1;\n 155:\t\t\tret2 = filemap_write_and_wait_range(inode-\u003ei_mapping, pos,\n 156:\t\t\t\t\t\t\t    endbyte);\n 157:\t\t\tif (!ret2) {\n 158:\t\t\t\tinvalidate_mapping_pages(inode-\u003ei_mapping,\n 159:\t\t\t\t\t\t\t pos \u003e\u003e PAGE_SHIFT,\n 160:\t\t\t\t\t\t\t endbyte \u003e\u003e PAGE_SHIFT);\n 161:\t\t\t\tif (ret \u003e 0)\n 162:\t\t\t\t\tret = generic_write_sync(iocb, ret);\n 163:\t\t\t} else {\n 164:\t\t\t\tret = ret2;\n 165:\t\t\t}\n 166:\t\t}\n 167:\t\n 168:\tout_unlock:\n 169:\t\tinode_unlock(inode);\n 170:\t\tif (status)\n 171:\t\t\ttrace_ext2_dio_write_buff_end(iocb, from, status);\n 172:\t\ttrace_ext2_dio_write_end(iocb, from, ret);\n 173:\t\treturn ret;\n 174:\t}\n 175:\t\n 176:\tstatic ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)\n 177:\t{\n 178:\t\tif (iocb-\u003eki_flags \u0026 IOCB_DIRECT)\n 179:\t\t\treturn ext2_dio_read_iter(iocb, to);\n 180:\t\n 181:\t\treturn generic_file_read_iter(iocb, to);\n 182:\t}\n 183:\t\n 184:\tstatic ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)\n 185:\t{\n 186:\t\tif (iocb-\u003eki_flags \u0026 IOCB_DIRECT)\n 187:\t\t\treturn ext2_dio_write_iter(iocb, from);\n 188:\t\n 189:\t\treturn generic_file_write_iter(iocb, from);\n 190:\t}\n 191:\t\n 192:\tstatic int ext2_file_open(struct inode *inode, struct file *filp)\n 193:\t{\n 194:\t\tfilp-\u003ef_mode |= FMODE_CAN_ODIRECT;\n 195:\t\treturn dquot_file_open(inode, filp);\n 196:\t}\n 197:\t\n 198:\tconst struct file_operations ext2_file_operations = {\n 199:\t\t.llseek\t\t= generic_file_llseek,\n"
}

gemini-3.8-flash

null

null

							input: 5204
							output: 30
							thoughts: 443
						

**Analyzing a DIO Write Bug in ext2**

Okay, let's break this down. It seems we're looking at a bug fix in `fs/ext2/file.c`, specifically within `ext2_dio_write_iter`. The issue arises during direct I/O (DIO) writes when they fall back to buffered writes, or in partial write scenarios where some bytes are written directly via DIO, and then the process switches to buffered writing using `generic_perform_write`.

The core problem, as I understand it, involves error handling. Previously, the code was flawed. If DIO managed to write *some* bytes successfully (`ret > 0`), and then `generic_perform_write` failed, the original code overwrote the `ret` value (which held the number of bytes successfully written via DIO) with the error code (`status`). Effectively, it threw away the progress made by DIO and just reported the buffered write error. The fix elegantly addresses this. Now, the code checks if `ret` is already positive (meaning some DIO writes succeeded). If so, it preserves that value. If `ret` is zero (no DIO bytes were written successfully), it assigns the error code from `status` to `ret`. This is a much more sensible approach; we're returning the number of bytes *actually* written, or the error if *nothing* was written.

A key question for me now is, is ext2 within reach for fuzzing using syzkaller? The answer seems to be a resounding yes! Ext2 is a mainstream filesystem in the Linux kernel and has been fuzzed by syzkaller for a long time. It can be mounted using loop devices, which syzkaller uses all the time. DIO writes to ext2 files are also directly accessible via standard syscalls, like `open(O_DIRECT)`, `pwritev`, `write`, `io_uring`, etc. So we can say that ext2 is indeed fuzzable.

I need to confirm ext2 location in `Kconfig`. Where is ext2 defined in `fs/ext2/Kconfig`? Need to check with `grepper` or `read-file`.

{
  "Expression": "config EXT2_FS",
  "PathPrefixes": [
    "fs/ext2"
  ]
}

{
  "Output": "fs/ext2/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nfs/ext2/Kconfig:2:config EXT2_FS\nfs/ext2/Kconfig-3-\ttristate \"Second extended fs support (DEPRECATED)\"\n--\nfs/ext2/Kconfig-20-\nfs/ext2/Kconfig:21:config EXT2_FS_XATTR\nfs/ext2/Kconfig-22-\tbool \"Ext2 extended attributes\"\n--\nfs/ext2/Kconfig-29-\nfs/ext2/Kconfig:30:config EXT2_FS_POSIX_ACL\nfs/ext2/Kconfig-31-\tbool \"Ext2 POSIX Access Control Lists\"\n--\nfs/ext2/Kconfig-39-\nfs/ext2/Kconfig:40:config EXT2_FS_SECURITY\nfs/ext2/Kconfig-41-\tbool \"Ext2 Security Labels\"\n"
}

gemini-3.8-flash

null

null

							input: 6375
							output: 33
							thoughts: 22
						

Okay, here's my take on those thoughts, tailored for an expert audience:

**Examining EXT2 Dependencies**

Alright, let's dive right in. My initial thought process is to quickly get a handle on the EXT2 filesystem's dependencies within the kernel configuration system. I want to understand what other components or settings need to be enabled or are logically linked before EXT2 support can be considered or built. I'm going to reach for `fs/ext2/Kconfig` – that's the canonical place for the kernel build system to define the EXT2_FS configuration option and its associated dependencies. I expect this file will give me the lowdown on any related module dependencies or boot parameters I should also be mindful of. Ultimately, I'm aiming to quickly map out the preconditions and contextual relationships surrounding EXT2_FS and its integration with the broader kernel configuration landscape.

{
  "File": "fs/ext2/Kconfig",
  "FirstLine": 1,
  "LineCount": 40
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0-only\n   2:\tconfig EXT2_FS\n   3:\t\ttristate \"Second extended fs support (DEPRECATED)\"\n   4:\t\tselect BUFFER_HEAD\n   5:\t\tselect FS_IOMAP\n   6:\t\thelp\n   7:\t\t  Ext2 is a standard Linux file system for hard disks.\n   8:\t\n   9:\t\t  This filesystem driver is deprecated because it does not properly\n  10:\t\t  support inode time stamps beyond 03:14:07 UTC on 19 January 2038.\n  11:\t\n  12:\t\t  Ext2 users are advised to use ext4 driver to access their filesystem.\n  13:\t\t  The driver is fully compatible, supports filesystems without journal\n  14:\t          or extents, and also supports larger time stamps if the filesystem\n  15:\t          is created with at least 256 byte inodes.\n  16:\t\n  17:\t\t  This code is kept as a simple reference for filesystem developers.\n  18:\t\n  19:\t\t  If unsure, say N.\n  20:\t\n  21:\tconfig EXT2_FS_XATTR\n  22:\t\tbool \"Ext2 extended attributes\"\n  23:\t\tdepends on EXT2_FS\n  24:\t\thelp\n  25:\t\t  Extended attributes are name:value pairs associated with inodes by\n  26:\t\t  the kernel or by users (see the attr(5) manual page for details).\n  27:\t\n  28:\t\t  If unsure, say N.\n  29:\t\n  30:\tconfig EXT2_FS_POSIX_ACL\n  31:\t\tbool \"Ext2 POSIX Access Control Lists\"\n  32:\t\tdepends on EXT2_FS_XATTR\n  33:\t\tselect FS_POSIX_ACL\n  34:\t\thelp\n  35:\t\t  Posix Access Control Lists (ACLs) support permissions for users and\n  36:\t\t  groups beyond the owner/group/world scheme.\n  37:\t\n  38:\t\t  If you don't know what Access Control Lists are, say N\n  39:\t\n  40:\tconfig EXT2_FS_SECURITY\n"
}

gemini-3.8-flash

null

null

							input: 7169
							output: 32
							thoughts: 46
						

Okay, let's dive into this. Here's my thought process on the matter:

**Analyzing Filesystem Write Operations**

Right, I need to see if this `ext2_dio_write_iter` pattern – or something analogous – exists in other filesystems. My first instinct is to compare implementations, to see if there's any commonality or divergent approaches to direct I/O writes. I'll need to explore the codebases of related filesystems; I'm thinking ext4, of course, but also something like xfs, and maybe even zonefs, if applicable, to understand their methods for direct I/O write operations. I’ll be specifically searching for functions or code segments that handle similar functionalities, paying attention to variations in naming conventions but scanning for similar core logic. The goal is to identify how these systems manage direct I/O.

{
  "Expression": "generic_perform_write.*status \u003c 0",
  "PathPrefixes": [
    "fs"
  ]
}

{
  "Output": "no matches"
}

gemini-3.8-flash

null

null

							input: 7443
							output: 29
							thoughts: 19
						

Okay, here's my thought process summarized, geared towards an expert:

**Investigating a Write Operation's Status**

Alright, let's get down to brass tacks. I need to figure out the status of a specific write operation, and the key I have is this identifier: `generic_perform_write`. That implies this isn't a *specific* file system or device; it's a more generalized, common function, which usually means it sits lower in the VFS or block layer.

Given that, I'm going to kick off a search directly within the `fs/` directory. That's where all the file system implementations live, so if it's generic, that's my best bet for a central point of definition or use. I'm assuming it's probably referenced or defined in the VFS layer, or that it’s used heavily by the file system implementations themselves. No time to waste, let's get the search going and see what pops up in `fs/`. This should give me a good initial overview.

{
  "Expression": "status = generic_perform_write",
  "PathPrefixes": [
    "fs"
  ]
}

{
  "Output": "fs/ext2/file.c=96=static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)\n--\nfs/ext2/file.c-145-\t\tpos = iocb-\u003eki_pos;\nfs/ext2/file.c:146:\t\tstatus = generic_perform_write(iocb, from);\nfs/ext2/file.c-147-\t\tif (unlikely(status \u003c 0)) {\n"
}

gemini-3.8-flash

null

null

							input: 7851
							output: 28
							thoughts: 17
						

Okay, here's my summarized thought process, presented as if I'm thinking it:

**Digging into the Filesystem Landscape**

Right, time to get to work. I need to understand how write operations are handled at a generic level within the filesystem. Let's start with a broad approach. I'm going to search, using my preferred tools, across the `fs/` directory. The keyword I'm most interested in finding is `generic_perform_write`. That sounds like a function name that could be a common entry point for write operations, so I'll see what comes up. This should help me identify where the core logic resides, before digging into any specific file systems. I anticipate that this will highlight a central function or a set of functions used to handle write operations in a general way.

{
  "Expression": "generic_perform_write\\(",
  "PathPrefixes": [
    "fs"
  ]
}

{
  "Output": "fs/ceph/file.c=2402=static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from)\n--\nfs/ceph/file.c-2586-\t\t */\nfs/ceph/file.c:2587:\t\twritten = generic_perform_write(iocb, from);\nfs/ceph/file.c-2588-\t\tceph_end_io_write(inode);\n--\nfs/ext2/file.c=96=static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)\n--\nfs/ext2/file.c-145-\t\tpos = iocb-\u003eki_pos;\nfs/ext2/file.c:146:\t\tstatus = generic_perform_write(iocb, from);\nfs/ext2/file.c-147-\t\tif (unlikely(status \u003c 0)) {\n--\nfs/ext4/file.c=348=static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,\n--\nfs/ext4/file.c-371-\telse\nfs/ext4/file.c:372:\t\tret = generic_perform_write(iocb, from);\nfs/ext4/file.c-373-\n--\nfs/f2fs/data.c=4254=static int f2fs_write_end(const struct kiocb *iocb,\n--\nfs/f2fs/data.c-4265-\t * should be PAGE_SIZE. Otherwise, we treat it with zero copied and\nfs/f2fs/data.c:4266:\t * let generic_perform_write() try to copy data again through copied=0.\nfs/f2fs/data.c-4267-\t */\n--\nfs/f2fs/file.c=5448=static ssize_t f2fs_buffered_write_iter(struct kiocb *iocb,\n--\nfs/f2fs/file.c-5457-\nfs/f2fs/file.c:5458:\tret = generic_perform_write(iocb, from);\nfs/f2fs/file.c-5459-\n--\nfs/nfs/file.c=737=ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)\n--\nfs/nfs/file.c-782-\tif (result \u003e 0)\nfs/nfs/file.c:783:\t\tresult = generic_perform_write(iocb, from);\nfs/nfs/file.c-784-\tnfs_end_io_write(inode);\n"
}

gemini-3.8-flash

null

null

							input: 8763
							output: 36
							thoughts: 481
						

**Analyzing the ext2 File System Write Path**

Okay, so I need to understand this change in `fs/ext2/file.c`. My initial instinct is to check the commit log using `git log -1` or `git log` on the file, to see the context. But wait, I recall we don't have the `git` tool available. That's fine, I remember seeing the diff directly, so I have the context.

Let me see... the diff shows a modification within the `ext2_dio_write_iter` function. I see the original code has `ret = status;`, but the new code checks `if (!ret)` before assigning.

Alright, so `ext2_dio_write_iter` is a static function. I'll need to figure out where this function is actually *called*. Jumping ahead, I see it's called by `ext2_file_write_iter` on line 187, conditional on `iocb->ki_flags & IOCB_DIRECT`. Aha! And `ext2_file_write_iter`, is actually `write_iter` from the `ext2_file_operations` structure.

Now, let's just make sure I have all the relevant information, so let me read lines 190 to 230 to confirm.

{
  "File": "fs/ext2/file.c",
  "FirstLine": 190,
  "LineCount": 40
}

{
  "Contents": " 190:\t}\n 191:\t\n 192:\tstatic int ext2_file_open(struct inode *inode, struct file *filp)\n 193:\t{\n 194:\t\tfilp-\u003ef_mode |= FMODE_CAN_ODIRECT;\n 195:\t\treturn dquot_file_open(inode, filp);\n 196:\t}\n 197:\t\n 198:\tconst struct file_operations ext2_file_operations = {\n 199:\t\t.llseek\t\t= generic_file_llseek,\n 200:\t\t.read_iter\t= ext2_file_read_iter,\n 201:\t\t.write_iter\t= ext2_file_write_iter,\n 202:\t\t.unlocked_ioctl = ext2_ioctl,\n 203:\t#ifdef CONFIG_COMPAT\n 204:\t\t.compat_ioctl\t= ext2_compat_ioctl,\n 205:\t#endif\n 206:\t\t.mmap_prepare\t= generic_file_mmap_prepare,\n 207:\t\t.open\t\t= ext2_file_open,\n 208:\t\t.release\t= ext2_release_file,\n 209:\t\t.fsync\t\t= simple_fsync,\n 210:\t\t.get_unmapped_area = thp_get_unmapped_area,\n 211:\t\t.splice_read\t= filemap_splice_read,\n 212:\t\t.splice_write\t= iter_file_splice_write,\n 213:\t\t.setlease\t= generic_setlease,\n 214:\t};\n 215:\t\n 216:\tconst struct inode_operations ext2_file_inode_operations = {\n 217:\t\t.listxattr\t= ext2_listxattr,\n 218:\t\t.getattr\t= ext2_getattr,\n 219:\t\t.setattr\t= ext2_setattr,\n 220:\t\t.get_inode_acl\t= ext2_get_acl,\n 221:\t\t.set_acl\t= ext2_set_acl,\n 222:\t\t.fiemap\t\t= ext2_fiemap,\n 223:\t\t.fileattr_get\t= ext2_fileattr_get,\n 224:\t\t.fileattr_set\t= ext2_fileattr_set,\n 225:\t};\n"
}

gemini-3.8-flash

null

null

							input: 10194
							output: 31
							thoughts: 1489
						

**Analysis of ext2 Direct I/O Write Logic for Fuzzing Eligibility**

Okay, so I'm diving into this `ext2_file_write_iter` function. I see that it calls `ext2_dio_write_iter` when the `IOCB_DIRECT` flag is set. The question is whether `ext2_dio_write_iter` is inlined. It's declared as `static`, so it *could* be. But then I remember that both `ext2_dio_write_iter` and `ext2_file_write_iter` are static, and both are very specific to ext2 write operations, so I'm thinking they're good candidates for targeting. I check the `ext2_file_operations` and see that `.write_iter` is explicitly set to `ext2_file_write_iter`. I think that both are potential FocusSymbols. I also check the FocusSymbol guidelines, and it says to target the specific implementation logic or API entry points.

Now, let's look at `ext2_dio_write_iter` to understand the flow. I see that it's for direct I/O writes to ext2 files opened with `O_DIRECT`. First the write is issued using `write()`, `pwritev()` etc. The Direct I/O is performed via `iomap_dio_rw()`. If the write is partial, due to alignment, extending file size, or other issues (like an ENOTBLK error, which is the key here), or if there's a fallback situation, the remaining part is handled by buffered writes via `generic_perform_write()`. Here's where the patch comes in. The code modifies the error handling. Before, if `generic_perform_write` returned an error (negative status), the function would return the error status. Now, it checks if there were previously written bytes using `if (!ret)`. If `ret > 0` (some bytes were written via DIO before the buffered write failed), the function *returns the number of written bytes* rather than the negative error code.

The critical thing is that I see that when `generic_perform_write()` fails, the code *still jumps* to `out_unlock` after DIO has already updated `iocb->ki_pos`. This means that if `ret > 0` and `status < 0`, `ret` (the number of bytes written) is returned, as per POSIX semantics. This is short write functionality.

Is this reachable code? Absolutely. It's core ext2 filesystem direct I/O. Does it modify executable code? Yes, this patch is altering the return value logic in `ext2_dio_write_iter`.

Given the guidelines for fuzzing eligibility, I see that any logic modification in reachable VFS/filesystem code warrants fuzzing. This patch clearly falls into that category since it affects ext2 direct I/O, which is accessed via standard system calls. Therefore, based on the criteria, `WorthFuzzing = true`.

Finally, regarding configuration, it looks like `CONFIG_EXT2_FS` (EXT2_FS) is the essential config required to have this code enabled. There are no other dependencies to this.

{
  "Expression": "source.*fs/ext2/Kconfig",
  "PathPrefixes": [
    "fs"
  ]
}

{
  "Output": "fs/Kconfig=33=if BLOCK\nfs/Kconfig-34-\nfs/Kconfig:35:source \"fs/ext2/Kconfig\"\nfs/Kconfig-36-source \"fs/ext4/Kconfig\"\n"
}

gemini-3.8-flash

null

null

							input: 12476
							output: 138
							thoughts: 404
						

**My Analysis of the ext2 Filesystem Fuzzing Configuration**

Okay, let's break this down. First, `fs/ext2/Kconfig` is nested within the `if BLOCK` condition in the broader `fs/Kconfig`. This means `BLOCK` is a necessary parent dependency. While `CONFIG_BLOCK` is practically always enabled, we can be more specific and include either `BLOCK` or just `EXT2_FS` in the final configuration. So, let's focus on `EXT2_FS` as the essential configuration item.

Next, I need to identify the key functions for focused fuzzing. The patch centers around `ext2_dio_write_iter`. Its entry point, `ext2_file_write_iter`, is in `ext2_file_operations`. Are there any others? I'll quickly check `fs/ext2/file.c` for related symbols. Alright, it looks like `ext2_dio_write_iter` and `ext2_file_write_iter` are indeed present.

Now, a crucial point: are these functions ubiquitous, or specific to ext2? No, thankfully, they are specific to the ext2 filesystem and its direct I/O write path. This means they are good targets for focused fuzzing.

Let's verify the instructions align perfectly:

*   **EnableConfigs**: We have `"EXT2_FS"` as the required kernel config, which is correct.
*   **FocusSymbols**: The list of functions is good: `["ext2_dio_write_iter", "ext2_file_write_iter"]` – these functions are specific to the ext2 filesystem and direct I/O writes.
*   **WorthFuzzing**: It's set to true, which I concur with.
*   **Reasoning**: The rationale is clear and concise. The patch modifies return value handling during partial/direct I/O writes, and the patch falls back to buffered I/O in ext2. Ext2 is fully reachable in standard VMs via loopback mounts and standard file I/O syscalls, which makes it ideal for fuzzing.

Finally, I'll perform a quick sanity check to confirm the tool call `set-results` is configured properly. Everything seems sound. I'm ready to proceed.

{
  "EnableConfigs": [
    "EXT2_FS"
  ],
  "FocusSymbols": [
    "ext2_dio_write_iter",
    "ext2_file_write_iter"
  ],
  "Reasoning": "The patch modifies error return handling in ext2_dio_write_iter() when generic_perform_write() fails after a partial direct I/O write, preserving the number of bytes written instead of overwriting with the error code. ext2 is directly reachable in virtualized environments via loop devices and standard file write operations (such as open with O_DIRECT and write/pwritev).",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "EXT2_FS"
  ],
  "FocusSymbols": [
    "ext2_dio_write_iter",
    "ext2_file_write_iter"
  ],
  "Reasoning": "The patch modifies error return handling in ext2_dio_write_iter() when generic_perform_write() fails after a partial direct I/O write, preserving the number of bytes written instead of overwriting with the error code. ext2 is directly reachable in virtualized environments via loop devices and standard file write operations (such as open with O_DIRECT and write/pwritev).",
  "WorthFuzzing": true
}

{
  "WorthFuzzing": true
}

null

core

null

{
  "KMSANReasoning": "The patch modifies scalar return value handling in ext2_dio_write_iter(): when a partial direct I/O write has already transferred some data (ret \u003e 0) and the subsequent buffered fallback write via generic_perform_write() fails (status \u003c 0), ret retains the number of bytes written rather than being overwritten with the negative error code.\n\nThis change does not allocate, initialize, read, or expose any kernel memory, nor does it copy uninitialized buffers or struct padding to userspace. All local variables involved (ret, status) are explicitly initialized. As there is no risk of uninitialized memory reads or information leaks, KMSAN is not applicable.",
  "NeedsKMSAN": false
}

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.

Target architecture: amd64

For your convenience, here is the diff of the changes:
commit 6a6988c4c560f62ce98dbf7ca377e9924a32bcab
Author: syz-cluster <triage@syzkaller.com>
Date:   Mon Nov 2 11:12:34 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index 67fe423c3828d8..8ddc149d488481 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -145,7 +145,8 @@ static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		pos = iocb->ki_pos;
 		status = generic_perform_write(iocb, from);
 		if (unlikely(status < 0)) {
-			ret = status;
+			if (!ret)
+				ret = status;
 			goto out_unlock;
 		}
 

gemini-3.8-flash

null

null

							input: 2218
							output: 36
							thoughts: 249
						

**Analyzing a Recent Patch in ext2's Direct I/O Write Implementation**

Okay, so I'm looking at this patch for `fs/ext2/file.c`, specifically focusing on the `ext2_dio_write_iter` function around line 145. My initial thought is to dive into the context surrounding this change. The diff itself is relatively straightforward; it seems we're modifying the error handling within the `ext2_dio_write_iter` function. More precisely, it seems like the original code potentially overwrites an existing error code with a later error. Now, in high-performance filesystems, that can be a critical mistake as it can mask more severe issues. Let's see... it looks like the change is to conditionally set `ret = status` only if `ret` is currently zero. That's good - it ensures that if an earlier error occurred during the process, it won't be clobbered by a later, possibly less critical, failure. This behavior aligns with the principle of returning the "most significant" error code in a sequence of operations. This change might seem small, but in a file system context where I/O can be extremely complex and error-prone, preserving the original error code is *crucial* for debugging and recovery. Now, I'll probably want to look at the surrounding code to ensure this doesn't introduce any regressions and that the error handling in this section remains robust. A quick scan seems good so far, looks like standard Linux kernel error handling practices are being maintained.

{
  "File": "fs/ext2/file.c",
  "FirstLine": 100,
  "LineCount": 80
}

{
  "Contents": " 100:\t\tssize_t ret;\n 101:\t\tunsigned int flags = 0;\n 102:\t\tunsigned long blocksize = inode-\u003ei_sb-\u003es_blocksize;\n 103:\t\tloff_t offset = iocb-\u003eki_pos;\n 104:\t\tloff_t count = iov_iter_count(from);\n 105:\t\tssize_t status = 0;\n 106:\t\n 107:\t\ttrace_ext2_dio_write_begin(iocb, from, 0);\n 108:\t\tinode_lock(inode);\n 109:\t\tret = generic_write_checks(iocb, from);\n 110:\t\tif (ret \u003c= 0)\n 111:\t\t\tgoto out_unlock;\n 112:\t\n 113:\t\tret = kiocb_modified(iocb);\n 114:\t\tif (ret)\n 115:\t\t\tgoto out_unlock;\n 116:\t\n 117:\t\t/* use IOMAP_DIO_FORCE_WAIT for unaligned or extending writes */\n 118:\t\tif (iocb-\u003eki_pos + iov_iter_count(from) \u003e i_size_read(inode) ||\n 119:\t\t   (!IS_ALIGNED(iocb-\u003eki_pos | iov_iter_alignment(from), blocksize)))\n 120:\t\t\tflags |= IOMAP_DIO_FORCE_WAIT;\n 121:\t\n 122:\t\tret = iomap_dio_rw(iocb, from, \u0026ext2_iomap_ops, \u0026ext2_dio_write_ops,\n 123:\t\t\t\t   flags, NULL, 0);\n 124:\t\n 125:\t\t/* ENOTBLK is magic return value for fallback to buffered-io */\n 126:\t\tif (ret == -ENOTBLK)\n 127:\t\t\tret = 0;\n 128:\t\n 129:\t\tif (ret \u003c 0 \u0026\u0026 ret != -EIOCBQUEUED)\n 130:\t\t\text2_write_failed(inode-\u003ei_mapping, offset + count);\n 131:\t\n 132:\t\t/* handle case for partial write and for fallback to buffered write */\n 133:\t\tif (ret \u003e= 0 \u0026\u0026 iov_iter_count(from)) {\n 134:\t\t\tloff_t pos, endbyte;\n 135:\t\t\tint ret2;\n 136:\t\n 137:\t\t\tiocb-\u003eki_flags \u0026= ~IOCB_DIRECT;\n 138:\t\n 139:\t\t\t/*\n 140:\t\t\t * Prevent concurrent direct I/O and buffered I/O to the same file\n 141:\t\t\t * range. Wait for in-flight DIO to finish before dirtying pages.\n 142:\t\t\t */\n 143:\t\t\tinode_dio_wait(inode);\n 144:\t\n 145:\t\t\tpos = iocb-\u003eki_pos;\n 146:\t\t\tstatus = generic_perform_write(iocb, from);\n 147:\t\t\tif (unlikely(status \u003c 0)) {\n 148:\t\t\t\tif (!ret)\n 149:\t\t\t\t\tret = status;\n 150:\t\t\t\tgoto out_unlock;\n 151:\t\t\t}\n 152:\t\n 153:\t\t\tret += status;\n 154:\t\t\tendbyte = pos + status - 1;\n 155:\t\t\tret2 = filemap_write_and_wait_range(inode-\u003ei_mapping, pos,\n 156:\t\t\t\t\t\t\t    endbyte);\n 157:\t\t\tif (!ret2) {\n 158:\t\t\t\tinvalidate_mapping_pages(inode-\u003ei_mapping,\n 159:\t\t\t\t\t\t\t pos \u003e\u003e PAGE_SHIFT,\n 160:\t\t\t\t\t\t\t endbyte \u003e\u003e PAGE_SHIFT);\n 161:\t\t\t\tif (ret \u003e 0)\n 162:\t\t\t\t\tret = generic_write_sync(iocb, ret);\n 163:\t\t\t} else {\n 164:\t\t\t\tret = ret2;\n 165:\t\t\t}\n 166:\t\t}\n 167:\t\n 168:\tout_unlock:\n 169:\t\tinode_unlock(inode);\n 170:\t\tif (status)\n 171:\t\t\ttrace_ext2_dio_write_buff_end(iocb, from, status);\n 172:\t\ttrace_ext2_dio_write_end(iocb, from, ret);\n 173:\t\treturn ret;\n 174:\t}\n 175:\t\n 176:\tstatic ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)\n 177:\t{\n 178:\t\tif (iocb-\u003eki_flags \u0026 IOCB_DIRECT)\n 179:\t\t\treturn ext2_dio_read_iter(iocb, to);\n"
}

gemini-3.8-flash

null

null

							input: 4087
							output: 163
							thoughts: 905
						

**Analyzing a Filesystem Write Patch: Return Value Correctness, Not Memory Safety**

Okay, let's break down this patch. My immediate concern is with how it handles return values in `ext2_dio_write_iter`. Specifically, it appears the direct I/O path can partially complete, but if the buffered write fallback via `generic_perform_write` fails, the *previous* code incorrectly overwrote the already-written byte count (`ret`) with the error code (`status`). That's a classic violation of POSIX semantics; if we've written *some* data, the function *must* return the number of bytes written (short write), and the error should be handled on the next call. This patch fixes that logic.

Now, my mind goes to memory safety. Is this related to uninitialized memory? Let's rule that out:

1.  **No kernel structs to userspace:** Nope. The return value is just a simple `ssize_t` – either the byte count or an error code. No complex kernel data is leaking.
2.  **No Uninitialized variables:**  `ret` *is* initialized, and `status` is also initialized. The logic, even the old broken one, doesn't hinge on an undefined state; it's a matter of *correct* return value handling, not initialization.
3.  **No Complex Data Structures:**  We're dealing with scalars (integers) and function calls. No memory allocation, no struct initialization – just return value processing.
4.  **No Bounds Issues:** `generic_perform_write` is copying data from user to the page cache. Returning a short write doesn't enable access to uninitialized data. The direct I/O (`iomap_dio_rw`) writes directly to disk from the user memory space.

Is KMSAN relevant here? Absolutely not. KMSAN tracks the *use* of uninitialized memory. This patch is about *correct* return value propagation. It has nothing to do with uninitialized reads or potential information leaks. KASAN/normal sanitizers are more focused on memory corruption. This is a straightforward logic fix for the return handling of partial writes during fallback from direct to buffered I/O. Neither KASAN nor KMSAN are really the right tool for detecting a logic error in return value handling like this.

Let me re-emphasize to be totally certain:
*   There's no uninitialized data being used or read.
*   No kernel memory with uninitialized fields is being copied to userspace.
*   The only thing returned is an integer representing a byte count or an error code.
*   Therefore, `NeedsKMSAN = false`.

I'm ready to write up the rationale: The patch fixes an incorrect return value in `ext2_dio_write_iter()` when direct I/O partially succeeds, but buffered write fails. It preserves the number of bytes written from direct I/O instead of overwriting the return value with the error from buffered write. There are no memory safety implications; the changes modify return value logic, involve no memory allocations, struct modifications, buffer initializations, or data copies to userspace. KMSAN is irrelevant because all local variables are initialized, and no kernel memory is read uninitialized or leaked to userspace. There's no reason to waste time on a KMSAN fuzzing session here.

{
  "KMSANReasoning": "The patch modifies scalar return value handling in ext2_dio_write_iter(): when a partial direct I/O write has already transferred some data (ret \u003e 0) and the subsequent buffered fallback write via generic_perform_write() fails (status \u003c 0), ret retains the number of bytes written rather than being overwritten with the negative error code.\n\nThis change does not allocate, initialize, read, or expose any kernel memory, nor does it copy uninitialized buffers or struct padding to userspace. All local variables involved (ret, status) are explicitly initialized. As there is no risk of uninitialized memory reads or information leaks, KMSAN is not applicable.",
  "NeedsKMSAN": false
}

{
  "KMSANReasoning": "The patch modifies scalar return value handling in ext2_dio_write_iter(): when a partial direct I/O write has already transferred some data (ret \u003e 0) and the subsequent buffered fallback write via generic_perform_write() fails (status \u003c 0), ret retains the number of bytes written rather than being overwritten with the negative error code.\n\nThis change does not allocate, initialize, read, or expose any kernel memory, nor does it copy uninitialized buffers or struct padding to userspace. All local variables involved (ret, status) are explicitly initialized. As there is no risk of uninitialized memory reads or information leaks, KMSAN is not applicable.",
  "NeedsKMSAN": false
}