CVE-2025-40351
Description
In the Linux kernel, the following vulnerability has been resolved:
hfsplus: fix KMSAN uninit-value issue in hfsplus_delete_cat()
The syzbot reported issue in hfsplus_delete_cat():
[ 70.682285][ T9333] ===================================================== [ 70.682943][ T9333] BUG: KMSAN: uninit-value in hfsplus_subfolders_dec+0x1d7/0x220 [ 70.683640][ T9333] hfsplus_subfolders_dec+0x1d7/0x220 [ 70.684141][ T9333] hfsplus_delete_cat+0x105d/0x12b0 [ 70.684621][ T9333] hfsplus_rmdir+0x13d/0x310 [ 70.685048][ T9333] vfs_rmdir+0x5ba/0x810 [ 70.685447][ T9333] do_rmdir+0x964/0xea0 [ 70.685833][ T9333] __x64_sys_rmdir+0x71/0xb0 [ 70.686260][ T9333] x64_sys_call+0xcd8/0x3cf0 [ 70.686695][ T9333] do_syscall_64+0xd9/0x1d0 [ 70.687119][ T9333] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 70.687646][ T9333] [ 70.687856][ T9333] Uninit was stored to memory at: [ 70.688311][ T9333] hfsplus_subfolders_inc+0x1c2/0x1d0 [ 70.688779][ T9333] hfsplus_create_cat+0x148e/0x1800 [ 70.689231][ T9333] hfsplus_mknod+0x27f/0x600 [ 70.689730][ T9333] hfsplus_mkdir+0x5a/0x70 [ 70.690146][ T9333] vfs_mkdir+0x483/0x7a0 [ 70.690545][ T9333] do_mkdirat+0x3f2/0xd30 [ 70.690944][ T9333] __x64_sys_mkdir+0x9a/0xf0 [ 70.691380][ T9333] x64_sys_call+0x2f89/0x3cf0 [ 70.691816][ T9333] do_syscall_64+0xd9/0x1d0 [ 70.692229][ T9333] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 70.692773][ T9333] [ 70.692990][ T9333] Uninit was stored to memory at: [ 70.693469][ T9333] hfsplus_subfolders_inc+0x1c2/0x1d0 [ 70.693960][ T9333] hfsplus_create_cat+0x148e/0x1800 [ 70.694438][ T9333] hfsplus_fill_super+0x21c1/0x2700 [ 70.694911][ T9333] mount_bdev+0x37b/0x530 [ 70.695320][ T9333] hfsplus_mount+0x4d/0x60 [ 70.695729][ T9333] legacy_get_tree+0x113/0x2c0 [ 70.696167][ T9333] vfs_get_tree+0xb3/0x5c0 [ 70.696588][ T9333] do_new_mount+0x73e/0x1630 [ 70.697013][ T9333] path_mount+0x6e3/0x1eb0 [ 70.697425][ T9333] __se_sys_mount+0x733/0x830 [ 70.697857][ T9333] __x64_sys_mount+0xe4/0x150 [ 70.698269][ T9333] x64_sys_call+0x2691/0x3cf0 [ 70.698704][ T9333] do_syscall_64+0xd9/0x1d0 [ 70.699117][ T9333] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 70.699730][ T9333] [ 70.699946][ T9333] Uninit was created at: [ 70.700378][ T9333] __alloc_pages_noprof+0x714/0xe60 [ 70.700843][ T9333] alloc_pages_mpol_noprof+0x2a2/0x9b0 [ 70.701331][ T9333] alloc_pages_noprof+0xf8/0x1f0 [ 70.701774][ T9333] allocate_slab+0x30e/0x1390 [ 70.702194][ T9333] ___slab_alloc+0x1049/0x33a0 [ 70.702635][ T9333] kmem_cache_alloc_lru_noprof+0x5ce/0xb20 [ 70.703153][ T9333] hfsplus_alloc_inode+0x5a/0xd0 [ 70.703598][ T9333] alloc_inode+0x82/0x490 [ 70.703984][ T9333] iget_locked+0x22e/0x1320 [ 70.704428][ T9333] hfsplus_iget+0x5c/0xba0 [ 70.704827][ T9333] hfsplus_btree_open+0x135/0x1dd0 [ 70.705291][ T9333] hfsplus_fill_super+0x1132/0x2700 [ 70.705776][ T9333] mount_bdev+0x37b/0x530 [ 70.706171][ T9333] hfsplus_mount+0x4d/0x60 [ 70.706579][ T9333] legacy_get_tree+0x113/0x2c0 [ 70.707019][ T9333] vfs_get_tree+0xb3/0x5c0 [ 70.707444][ T9333] do_new_mount+0x73e/0x1630 [ 70.707865][ T9333] path_mount+0x6e3/0x1eb0 [ 70.708270][ T9333] __se_sys_mount+0x733/0x830 [ 70.708711][ T9333] __x64_sys_mount+0xe4/0x150 [ 70.709158][ T9333] x64_sys_call+0x2691/0x3cf0 [ 70.709630][ T9333] do_syscall_64+0xd9/0x1d0 [ 70.710053][ T9333] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 70.710611][ T9333] [ 70.710842][ T9333] CPU: 3 UID: 0 PID: 9333 Comm: repro Not tainted 6.12.0-rc6-dirty #17 [ 70.711568][ T9333] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 70.712490][ T9333] ===================================================== [ 70.713085][ T9333] Disabling lock debugging due to kernel taint [ 70.713618][ T9333] Kernel panic - not syncing: kmsan.panic set ... [ 70.714159][ T9333] ---truncated---
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
An uninitialized memory access in the Linux kernel's HFS+ filesystem deletion function could lead to information disclosure or system crash.
Vulnerability
Overview
CVE-2025-40351 is a kernel memory uninitialization issue in the HFS+ filesystem implementation, specifically in the hfsplus_delete_cat() function. The bug was discovered by syzbot and reported as a KMSAN (Kernel Memory Sanitizer) warning. The root cause is that when deleting a directory entry, the code may access a field that was never properly initialized, leading to an uninit-value condition.[1]
Exploitation
Path
The vulnerability can be triggered by performing directory operations (e.g., rmdir) on a crafted or corrupted HFS+ filesystem image. An attacker with local access and the ability to mount a malicious HFS+ filesystem (or trigger the operations on an existing mount) can exploit this issue. No special privileges beyond basic file system access are required, as the call chain involves common VFS operations like vfs_rmdir.[2]
Impact
A successful exploit could result in the kernel reading uninitialized memory, potentially leaking sensitive information from kernel memory to user space. Additionally, the uninitialized value may cause undefined behavior, including kernel crashes (denial of service). The KMSAN report indicates the uninit value is later used in hfsplus_subfolders_dec, which could corrupt internal filesystem state.[3]
Mitigation
The fix has been applied to the Linux kernel source tree and backported to stable branches. Users should update their kernels to versions containing the commits referenced by [1], [2], [3], and [4]. There is no workaround other than avoiding mounting untrusted HFS+ filesystems until patched.
AI Insight generated on May 19, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
2Patches
8a2bee43b4516b07630afe1679df3c241fbf61b9e5ade272f2bb8bc99b1a7295527bfdefd4891bf2b09c39b3d15a75891Vulnerability mechanics
Generated on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
8- git.kernel.org/stable/c/1b9e5ade272f8be6421c9eea4c4f6810180017f9nvd
- git.kernel.org/stable/c/295527bfdefd5bf31ec8218e2891a65777141d05nvd
- git.kernel.org/stable/c/2bb8bc99b1a7a46d83f95c46f530305f6df84eafnvd
- git.kernel.org/stable/c/4891bf2b09c313622a6e07d7f108aa5e123c768dnvd
- git.kernel.org/stable/c/9b3d15a758910bb98ba8feb4109d99cc67450ee4nvd
- git.kernel.org/stable/c/9df3c241fbf69edce968b20eeeeb3f6da34af041nvd
- git.kernel.org/stable/c/a2bee43b451615531ae6f3cf45054f02915ef885nvd
- git.kernel.org/stable/c/b07630afe1671096dc64064190cae3b6165cf6e4nvd
News mentions
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