Description
In the Linux kernel, the following vulnerability has been resolved:

f2fs: validate ACL entry sizes in f2fs_acl_from_disk()

f2fs_acl_count() only validates the aggregate ACL xattr length. A
malformed ACL can still place ACL_USER or ACL_GROUP in a slot that only
contains struct f2fs_acl_entry_short bytes, and f2fs_acl_from_disk()
then reads entry->e_id before verifying that a full entry fits.

Require a short entry before reading e_tag and e_perm, and require a
full entry before reading e_id for ACL_USER and ACL_GROUP. Return
-EFSCORRUPTED from these new truncated-entry checks, while keeping the
pre-existing -EINVAL paths unchanged.

Validation reproduced this kernel report:
KASAN slab-out-of-bounds in __f2fs_get_acl+0x6fb/0x7e0
RIP: 0033:0x7f4b835ea7aa
The buggy address belongs to the object at ffff888114589960 which belongs
to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes to the right of allocated 8-byte
region [ffff888114589960, ffff888114589968)
Read of size 4
Call trace:
dump_stack_lvl+0x66/0xa0 (?:?)
print_report+0xce/0x630 (?:?)
__f2fs_get_acl+0x6fb/0x7e0 (fs/f2fs/acl.c:169)
srso_alias_return_thunk+0x5/0xfbef5 (?:?)
__virt_addr_valid+0x224/0x430 (?:?)
kasan_report+0xe0/0x110 (?:?)
__f2fs_get_acl+0x5/0x7e0 (fs/f2fs/acl.c:169)
__get_acl+0x281/0x380 (?:?)
vfs_get_acl+0x10b/0x190 (?:?)
do_get_acl+0x2a/0x410 (?:?)
do_get_acl+0x9/0x410 (?:?)
do_getxattr+0xe8/0x260 (?:?)
filename_getxattr+0xd1/0x140 (?:?)
do_getname+0x2d/0x2d0 (?:?)
path_getxattrat+0x16c/0x200 (?:?)
lock_release+0xc8/0x290 (?:?)
cgroup_update_frozen+0x9d/0x320 (?:?)
lockdep_hardirqs_on_prepare+0xea/0x1a0 (?:?)
trace_hardirqs_on+0x1a/0x170 (?:?)
_raw_spin_unlock_irq+0x28/0x50 (?:?)
do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)
entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)
Published: 2026-07-19
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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History

Sun, 19 Jul 2026 12:15:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: f2fs: validate ACL entry sizes in f2fs_acl_from_disk() f2fs_acl_count() only validates the aggregate ACL xattr length. A malformed ACL can still place ACL_USER or ACL_GROUP in a slot that only contains struct f2fs_acl_entry_short bytes, and f2fs_acl_from_disk() then reads entry->e_id before verifying that a full entry fits. Require a short entry before reading e_tag and e_perm, and require a full entry before reading e_id for ACL_USER and ACL_GROUP. Return -EFSCORRUPTED from these new truncated-entry checks, while keeping the pre-existing -EINVAL paths unchanged. Validation reproduced this kernel report: KASAN slab-out-of-bounds in __f2fs_get_acl+0x6fb/0x7e0 RIP: 0033:0x7f4b835ea7aa The buggy address belongs to the object at ffff888114589960 which belongs to the cache kmalloc-8 of size 8 The buggy address is located 0 bytes to the right of allocated 8-byte region [ffff888114589960, ffff888114589968) Read of size 4 Call trace: dump_stack_lvl+0x66/0xa0 (?:?) print_report+0xce/0x630 (?:?) __f2fs_get_acl+0x6fb/0x7e0 (fs/f2fs/acl.c:169) srso_alias_return_thunk+0x5/0xfbef5 (?:?) __virt_addr_valid+0x224/0x430 (?:?) kasan_report+0xe0/0x110 (?:?) __f2fs_get_acl+0x5/0x7e0 (fs/f2fs/acl.c:169) __get_acl+0x281/0x380 (?:?) vfs_get_acl+0x10b/0x190 (?:?) do_get_acl+0x2a/0x410 (?:?) do_get_acl+0x9/0x410 (?:?) do_getxattr+0xe8/0x260 (?:?) filename_getxattr+0xd1/0x140 (?:?) do_getname+0x2d/0x2d0 (?:?) path_getxattrat+0x16c/0x200 (?:?) lock_release+0xc8/0x290 (?:?) cgroup_update_frozen+0x9d/0x320 (?:?) lockdep_hardirqs_on_prepare+0xea/0x1a0 (?:?) trace_hardirqs_on+0x1a/0x170 (?:?) _raw_spin_unlock_irq+0x28/0x50 (?:?) do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)
Title f2fs: validate ACL entry sizes in f2fs_acl_from_disk()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-07-19T12:02:14.771Z

Reserved: 2026-07-19T07:54:57.014Z

Link: CVE-2026-63814

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