GHSA-QX34-9C4P-JVQ8
Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix use-after-free of fp->owner.name in durable handle owner check
Two concurrent SMB2 durable reconnects (DH2C/DHnC) on the same persistent_id race the fp->owner.name compare-read in ksmbd_vfs_compare_durable_owner() against the kfree() in ksmbd_reopen_durable_fd()'s reopen-success path. fp->owner.name is a standalone kstrdup() buffer whose lifetime is independent of the fp refcount, and the two sites share no lock: the compare reads the buffer while the reopen frees it, so the strcmp() can dereference freed memory.
Commit 7ce4fc40018d ("ksmbd: fix durable reconnect double-bind race in ksmbd_reopen_durable_fd") made the fp->conn claim atomic under global_ft.lock (closing the owner.name double-free and the ksmbd_file write-UAF), but the compare-read versus reopen-free pair was left unserialized.
BUG: KASAN: slab-use-after-free in strcmp+0x2c/0x80 Read of size 1 by task kworker strcmp ksmbd_vfs_compare_durable_owner smb2_check_durable_oplock smb2_open Freed by task kworker: kfree ksmbd_reopen_durable_fd smb2_open Allocated by task kworker: kstrdup session_fd_check smb2_session_logoff The buggy address belongs to the cache kmalloc-8
Serialize both sides of the race with fp->f_lock. The global durable file-table lock still protects the durable reconnect claim, but fp->owner.name is per-open state and does not need to block unrelated durable table lookups or reconnects. The teardown is left at its existing location after the reopen-success point so that an __open_id() rollback still retains owner.name for a later legitimate reconnect to verify.
{
"affected": [],
"aliases": [
"CVE-2026-72381"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:22:11Z",
"severity": "CRITICAL"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free of fp-\u003eowner.name in durable handle owner check\n\nTwo concurrent SMB2 durable reconnects (DH2C/DHnC) on the same\npersistent_id race the fp-\u003eowner.name compare-read in\nksmbd_vfs_compare_durable_owner() against the kfree() in\nksmbd_reopen_durable_fd()\u0027s reopen-success path. fp-\u003eowner.name is a\nstandalone kstrdup() buffer whose lifetime is independent of the fp\nrefcount, and the two sites share no lock: the compare reads the buffer\nwhile the reopen frees it, so the strcmp() can dereference freed memory.\n\nCommit 7ce4fc40018d (\"ksmbd: fix durable reconnect double-bind race in\nksmbd_reopen_durable_fd\") made the fp-\u003econn claim atomic under\nglobal_ft.lock (closing the owner.name double-free and the ksmbd_file\nwrite-UAF), but the compare-read versus reopen-free pair was left\nunserialized.\n\n BUG: KASAN: slab-use-after-free in strcmp+0x2c/0x80\n Read of size 1 by task kworker\n strcmp\n ksmbd_vfs_compare_durable_owner\n smb2_check_durable_oplock\n smb2_open\n Freed by task kworker:\n kfree\n ksmbd_reopen_durable_fd\n smb2_open\n Allocated by task kworker:\n kstrdup\n session_fd_check\n smb2_session_logoff\n The buggy address belongs to the cache kmalloc-8\n\nSerialize both sides of the race with fp-\u003ef_lock. The global durable\nfile-table lock still protects the durable reconnect claim, but\nfp-\u003eowner.name is per-open state and does not need to block unrelated\ndurable table lookups or reconnects. The teardown is left at its\nexisting location after the reopen-success point so that an __open_id()\nrollback still retains owner.name for a later legitimate reconnect to\nverify.",
"id": "GHSA-qx34-9c4p-jvq8",
"modified": "2026-08-17T06:33:26Z",
"published": "2026-08-15T06:32:22Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72381"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/38637163501fd9e2f684b8cd275d0db5d79f37c6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5a5ac2852cd326529d02f778bc1aa6184701f4d7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/93d4d46bf9d442a12ea87278049ec416962c627f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ed98719be41389d416953b8ef9f07a07dfea6b2b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fb978d72052704c6b06c6b0f129fcd60b77169f5"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
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