GHSA-99P6-GFCM-83G8
Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33In the Linux kernel, the following vulnerability has been resolved:
bpf: fix UAF by restoring RCU-delayed inode freeing in bpffs
commit 4f375ade6aa9 ("bpf: Avoid RCU context warning when unpinning htab with internal structs") moved inode cleanup from ->free_inode() into ->destroy_inode() to avoid sleeping in RCU context when calling bpf_any_put(). However this removed the RCU delay on freeing the inode itself and the cached symlink body (i_link), both of which can be accessed by RCU pathwalk (pick_link, may_lookup etc.).
This causes a use-after-free when a concurrent unlinkat() drops the last inode reference and destroy_inode() frees the inode immediately, while another task is still walking the path in RCU mode and reads inode->i_opflags (offset +2) inside current_time() -> is_mgtime().
KASAN reports: BUG: KASAN: slab-use-after-free in is_mgtime include/linux/fs.h:2313 Read of size 2 at addr ffff8880407e4282 (offset +2 = i_opflags)
The rules (per Al Viro): ->destroy_inode() called immediately, can sleep, use for blocking cleanup e.g. bpf_any_put() ->free_inode() called after RCU grace period, use for freeing inode and anything RCU-accessible e.g. i_link
Fix: split the two concerns properly: - keep bpf_any_put() in bpf_destroy_inode() since it is blocking and needs to run promptly - introduce bpf_free_inode() to handle kfree(i_link) and free_inode_nonrcu() with proper RCU delay, preventing the UAF
{
"affected": [],
"aliases": [
"CVE-2026-74363"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:22:37Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: fix UAF by restoring RCU-delayed inode freeing in bpffs\n\ncommit 4f375ade6aa9 (\"bpf: Avoid RCU context warning when unpinning\nhtab with internal structs\") moved inode cleanup from -\u003efree_inode()\ninto -\u003edestroy_inode() to avoid sleeping in RCU context when calling\nbpf_any_put(). However this removed the RCU delay on freeing the\ninode itself and the cached symlink body (i_link), both of which\ncan be accessed by RCU pathwalk (pick_link, may_lookup etc.).\n\nThis causes a use-after-free when a concurrent unlinkat() drops the\nlast inode reference and destroy_inode() frees the inode immediately,\nwhile another task is still walking the path in RCU mode and reads\ninode-\u003ei_opflags (offset +2) inside current_time() -\u003e is_mgtime().\n\nKASAN reports:\n BUG: KASAN: slab-use-after-free in is_mgtime include/linux/fs.h:2313\n Read of size 2 at addr ffff8880407e4282 (offset +2 = i_opflags)\n\nThe rules (per Al Viro):\n -\u003edestroy_inode() called immediately, can sleep, use for blocking\n cleanup e.g. bpf_any_put()\n -\u003efree_inode() called after RCU grace period, use for freeing\n inode and anything RCU-accessible e.g. i_link\n\nFix: split the two concerns properly:\n - keep bpf_any_put() in bpf_destroy_inode() since it is blocking\n and needs to run promptly\n - introduce bpf_free_inode() to handle kfree(i_link) and\n free_inode_nonrcu() with proper RCU delay, preventing the UAF",
"id": "GHSA-99p6-gfcm-83g8",
"modified": "2026-08-17T06:33:40Z",
"published": "2026-08-15T06:32:31Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74363"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0497ff765746d9b2d17445c8f7cc737b36c0152a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/53649846e0437d1d9b7cb993cfe54c367addf7ae"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5fecb71c10c28aef276ba49c718dc961745fdcf0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/61f19729728243c82476dee31315143ed3275e7f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b93c55b4932dd7e32dca8cf34a3443cc87a02906"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c70d0f9114c3cc156f6029a400c4eb7e6f7c82b2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ea1c243c39e32b7fc1c2edfe32081ff7e30a877c"
}
],
"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"
}
]
}
Sightings
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Nomenclature
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