hfsplus: fix slab-out-of-bounds read in hfsplus_strcasecmp()
CVE: CVE-2025-40088
Component: kernel
CWE: CWE-125
Severity: Low
CVSS v3: 5.6/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Release date: 2025-10-30T00:00:00+00:00

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]  <TASK>
[  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---

Statement: This vulnerability requires local access and the ability to mount HFS+ filesystems. The out-of-bounds read could lead to information disclosure or system instability. Systems that do not use HFS+ filesystem support are not affected.

Remediation:
To mitigate this issue, prevent the hfsplus module from being loaded if HFS+ filesystem support is not required. See https://access.redhat.com/solutions/41278 for instructions on how to blacklist a kernel module.