CVE-2025-40088
Description
In the Linux kernel, the following vulnerability has been resolved:
hfsplus: fix slab-out-of-bounds read in hfsplus_strcasecmp()
The hfsplus_strcasecmp() logic can trigger the issue:
[ 117.317703][ T9855] ================================================================== [ 117.318353][ T9855] BUG: KASAN: slab-out-of-bounds in hfsplus_strcasecmp+0x1bc/0x490 [ 117.318991][ T9855] Read of size 2 at addr ffff88802160f40c by task repro/9855 [ 117.319577][ T9855] [ 117.319773][ T9855] CPU: 0 UID: 0 PID: 9855 Comm: repro Not tainted 6.17.0-rc6 #33 PREEMPT(full) [ 117.319780][ T9855] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 117.319783][ T9855] Call Trace: [ 117.319785][ T9855] [ 117.319788][ T9855] dump_stack_lvl+0x1c1/0x2a0 [ 117.319795][ T9855] ? __virt_addr_valid+0x1c8/0x5c0 [ 117.319803][ T9855] ? __pfx_dump_stack_lvl+0x10/0x10 [ 117.319808][ T9855] ? rcu_is_watching+0x15/0xb0 [ 117.319816][ T9855] ? lock_release+0x4b/0x3e0 [ 117.319821][ T9855] ? __kasan_check_byte+0x12/0x40 [ 117.319828][ T9855] ? __virt_addr_valid+0x1c8/0x5c0 [ 117.319835][ T9855] ? __virt_addr_valid+0x4a5/0x5c0 [ 117.319842][ T9855] print_report+0x17e/0x7e0 [ 117.319848][ T9855] ? __virt_addr_valid+0x1c8/0x5c0 [ 117.319855][ T9855] ? __virt_addr_valid+0x4a5/0x5c0 [ 117.319862][ T9855] ? __phys_addr+0xd3/0x180 [ 117.319869][ T9855] ? hfsplus_strcasecmp+0x1bc/0x490 [ 117.319876][ T9855] kasan_report+0x147/0x180 [ 117.319882][ T9855] ? hfsplus_strcasecmp+0x1bc/0x490 [ 117.319891][ T9855] hfsplus_strcasecmp+0x1bc/0x490 [ 117.319900][ T9855] ? __pfx_hfsplus_cat_case_cmp_key+0x10/0x10 [ 117.319906][ T9855] hfs_find_rec_by_key+0xa9/0x1e0 [ 117.319913][ T9855] __hfsplus_brec_find+0x18e/0x470 [ 117.319920][ T9855] ? __pfx_hfsplus_bnode_find+0x10/0x10 [ 117.319926][ T9855] ? __pfx_hfs_find_rec_by_key+0x10/0x10 [ 117.319933][ T9855] ? __pfx___hfsplus_brec_find+0x10/0x10 [ 117.319942][ T9855] hfsplus_brec_find+0x28f/0x510 [ 117.319949][ T9855] ? __pfx_hfs_find_rec_by_key+0x10/0x10 [ 117.319956][ T9855] ? __pfx_hfsplus_brec_find+0x10/0x10 [ 117.319963][ T9855] ? __kmalloc_noprof+0x2a9/0x510 [ 117.319969][ T9855] ? hfsplus_find_init+0x8c/0x1d0 [ 117.319976][ T9855] hfsplus_brec_read+0x2b/0x120 [ 117.319983][ T9855] hfsplus_lookup+0x2aa/0x890 [ 117.319990][ T9855] ? __pfx_hfsplus_lookup+0x10/0x10 [ 117.320003][ T9855] ? d_alloc_parallel+0x2f0/0x15e0 [ 117.320008][ T9855] ? __lock_acquire+0xaec/0xd80 [ 117.320013][ T9855] ? __pfx_d_alloc_parallel+0x10/0x10 [ 117.320019][ T9855] ? __raw_spin_lock_init+0x45/0x100 [ 117.320026][ T9855] ? __init_waitqueue_head+0xa9/0x150 [ 117.320034][ T9855] __lookup_slow+0x297/0x3d0 [ 117.320039][ T9855] ? __pfx___lookup_slow+0x10/0x10 [ 117.320045][ T9855] ? down_read+0x1ad/0x2e0 [ 117.320055][ T9855] lookup_slow+0x53/0x70 [ 117.320065][ T9855] walk_component+0x2f0/0x430 [ 117.320073][ T9855] path_lookupat+0x169/0x440 [ 117.320081][ T9855] filename_lookup+0x212/0x590 [ 117.320089][ T9855] ? __pfx_filename_lookup+0x10/0x10 [ 117.320098][ T9855] ? strncpy_from_user+0x150/0x290 [ 117.320105][ T9855] ? getname_flags+0x1e5/0x540 [ 117.320112][ T9855] user_path_at+0x3a/0x60 [ 117.320117][ T9855] __x64_sys_umount+0xee/0x160 [ 117.320123][ T9855] ? __pfx___x64_sys_umount+0x10/0x10 [ 117.320129][ T9855] ? do_syscall_64+0xb7/0x3a0 [ 117.320135][ T9855] ? entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 117.320141][ T9855] ? entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 117.320145][ T9855] do_syscall_64+0xf3/0x3a0 [ 117.320150][ T9855] ? exc_page_fault+0x9f/0xf0 [ 117.320154][ T9855] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 117.320158][ T9855] RIP: 0033:0x7f7dd7908b07 [ 117.320163][ T9855] Code: 23 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 08 [ 117.320167][ T9855] RSP: 002b:00007ffd5ebd9698 EFLAGS: 00000202 ---truncated---
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
A slab-out-of-bounds read vulnerability in the Linux kernel's HFS+ filesystem driver (hfsplus_strcasecmp) can be triggered via a crafted filesystem image.
Vulnerability
Details
CVE-2025-40088 is a slab-out-of-bounds read vulnerability in the Linux kernel's HFS+ filesystem implementation. The bug resides in the hfsplus_strcasecmp() function, which is used to compare case-insensitive filenames stored in the HFS+ catalog. Due to insufficient bounds checking, the function can read beyond the allocated slab buffer, as demonstrated by the KASAN report showing a read of size 2 at an out-of-bounds address [1].
Attack
Vector
Exploitation requires a local attacker to mount a specially crafted HFS+ filesystem image. The vulnerable code path is reachable through normal filesystem operations such as directory lookups or file access that trigger catalog record comparisons. No special privileges beyond the ability to mount a filesystem are needed; the attacker only needs to supply the malicious image and mount it on a system with the HFS+ module loaded [1].
Impact
A successful out-of-bounds read can leak kernel memory contents, potentially disclosing sensitive information. Depending on the memory layout, the read may also cause a kernel crash (denial of service) due to accessing unmapped memory. The kernel's KASAN (Kernel Address Sanitizer) report confirms the bug is a "slab-out-of-bounds" violation, which could lead to system instability or information disclosure [1].
Mitigation
The vulnerability was fixed in Linux kernel commits 4bc081ba6c52, 603158d4efa9, ef250c3edd99, and 7ab44236b32e [2][3][4]. Users should apply the appropriate kernel update for their distribution. No workaround is available; users must ensure they are running a kernel containing the fix.
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
8603158d4efa9ef250c3edd997ab44236b32eb47a75b6f7624f5ab4a9c6ab586c75dfd1d24bc081ba6c5242520df65bf6Vulnerability 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/42520df65bf67189541a425f7d36b0b3e7bd7844nvd
- git.kernel.org/stable/c/4bc081ba6c52b0c88c92701e3fbc33c7e2277afbnvd
- git.kernel.org/stable/c/4f5ab4a9c6abd8b0d713cc2b7b041bc10d70f241nvd
- git.kernel.org/stable/c/586c75dfd1d265c4150f6529debb85c9d62e101fnvd
- git.kernel.org/stable/c/603158d4efa98a13a746bd586c20f194f4a31ec8nvd
- git.kernel.org/stable/c/7ab44236b32ed41eb0636797e8e8e885a2f3b18anvd
- git.kernel.org/stable/c/b47a75b6f762321f9eb6f31aab7bce47a37063b7nvd
- git.kernel.org/stable/c/ef250c3edd995d7bb5a5e5122ffad1c28a8686ebnvd
News mentions
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