GHSA-Q88C-G8P8-M4R9
Vulnerability from github – Published: 2026-07-19 12:30 – Updated: 2026-07-20 15:31In 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 (?:?)
{
"affected": [],
"aliases": [
"CVE-2026-63814"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-19T12:16:54Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: validate ACL entry sizes in f2fs_acl_from_disk()\n\nf2fs_acl_count() only validates the aggregate ACL xattr length. A\nmalformed ACL can still place ACL_USER or ACL_GROUP in a slot that only\ncontains struct f2fs_acl_entry_short bytes, and f2fs_acl_from_disk()\nthen reads entry-\u003ee_id before verifying that a full entry fits.\n\nRequire a short entry before reading e_tag and e_perm, and require a\nfull entry before reading e_id for ACL_USER and ACL_GROUP. Return\n-EFSCORRUPTED from these new truncated-entry checks, while keeping the\npre-existing -EINVAL paths unchanged.\n\nValidation reproduced this kernel report:\nKASAN slab-out-of-bounds in __f2fs_get_acl+0x6fb/0x7e0\nRIP: 0033:0x7f4b835ea7aa\nThe buggy address belongs to the object at ffff888114589960 which belongs\nto the cache kmalloc-8 of size 8\nThe buggy address is located 0 bytes to the right of allocated 8-byte\nregion [ffff888114589960, ffff888114589968)\nRead of size 4\nCall trace:\n dump_stack_lvl+0x66/0xa0 (?:?)\n print_report+0xce/0x630 (?:?)\n __f2fs_get_acl+0x6fb/0x7e0 (fs/f2fs/acl.c:169)\n srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n __virt_addr_valid+0x224/0x430 (?:?)\n kasan_report+0xe0/0x110 (?:?)\n __f2fs_get_acl+0x5/0x7e0 (fs/f2fs/acl.c:169)\n __get_acl+0x281/0x380 (?:?)\n vfs_get_acl+0x10b/0x190 (?:?)\n do_get_acl+0x2a/0x410 (?:?)\n do_get_acl+0x9/0x410 (?:?)\n do_getxattr+0xe8/0x260 (?:?)\n filename_getxattr+0xd1/0x140 (?:?)\n do_getname+0x2d/0x2d0 (?:?)\n path_getxattrat+0x16c/0x200 (?:?)\n lock_release+0xc8/0x290 (?:?)\n cgroup_update_frozen+0x9d/0x320 (?:?)\n lockdep_hardirqs_on_prepare+0xea/0x1a0 (?:?)\n trace_hardirqs_on+0x1a/0x170 (?:?)\n _raw_spin_unlock_irq+0x28/0x50 (?:?)\n do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)\n entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)",
"id": "GHSA-q88c-g8p8-m4r9",
"modified": "2026-07-20T15:31:47Z",
"published": "2026-07-19T12:30:23Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63814"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1ddf3fd21c4c652f9cab5552515c04a166662306"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/442ca20c54038e2400cf28aaa944cf1de2c8e65d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4e2a96ec7236e248e706850568e0a925fd21b588"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5d8a39649947a4e86c8fbc682d7fc0041b8d109a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/733cd8474e6d763d75ed96f3f2b98a25480cf2b9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/aba4f94ac1832c7299c33e1b4fe5f87eef6dc8f1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c4810ada31e80cbe4011467c4f3b1e93f94134f3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ff83de56882cb8466184d322abece2589258ca56"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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