ksmbd: fix use-after-free of a deferred file_lock on double SMB2_CANCEL_CVE-2026-53198

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free of a deferred file_lock on double SMB2_CANCEL\n\nA deferred byte-range lock (an SMB2_LOCK that blocks) registers an async work on\nconn->async_requests via setup_async_work(), with cancel_fn =\nsmb2_remove_blocked_lock and cancel_argv[0] pointing at the struct file_lock.\n\nWhen the request is cancelled, the worker frees the file_lock with\nlocks_free_lock() and takes the cancelled early-exit, which \"goto out\"s and never\nreaches release_async_work() -- the only site that unlinks the work from\nconn->async_requests and clears cancel_fn/cancel_argv. The work therefore stays\nmatchable on async_requests with a live cancel_fn pointing at the freed file_lock,\nuntil connection teardown finally runs release_async_work().\n\nsmb2_cancel() fires cancel_fn unconditionally with no state guard, so a second\nSMB2_CANCEL for the same AsyncId, arriving in that window, re-runs\nsmb2_remove_blocked_lock() on the freed file_lock -- a slab use-after-free:\n\n  BUG: KASAN: slab-use-after-free in __locks_delete_block\n    __locks_delete_block\n    locks_delete_block\n    ksmbd_vfs_posix_lock_unblock\n    smb2_remove_blocked_lock\n    smb2_cancel                 <- 2nd SMB2_CANCEL fires cancel_fn\n    handle_ksmbd_work\n  Allocated by ...: locks_alloc_lock <- smb2_lock\n  Freed by ...:     locks_free_lock  <- smb2_lock (cancelled branch)\n  ... cache file_lock_cache of size 192\n\nReproduced on mainline with KASAN by an authenticated SMB client.\n\nSkip a work whose state is already KSMBD_WORK_CANCELLED so its cancel callback\ncannot be fired a second time.",
    "published": "2026-06-25T08:39:07.650Z",
    "modified": "2026-06-28T06:40:15.304Z",
    "type": "cve",
    "title": "ksmbd: fix use-after-free of a deferred file_lock on double SMB2_CANCEL",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/b7063c7426ea5a4d15e01b60538718765392f49d\nhttps://git.kernel.org/stable/c/0da2e073f9cbf4985a0fd9acb71bc5ff599f8afd\nhttps://git.kernel.org/stable/c/89ae9df09d2c1fb4a4eb495c113a7ce1dca34147\nhttps://git.kernel.org/stable/c/14d2eee0193ac3cd1bf3d014373449f0b8d35d6d\nhttps://git.kernel.org/stable/c/2b2eda2821cff1d1b5a423b6ee7d8fc6fbc8e694\nhttps://git.kernel.org/stable/c/f580d27e8928828693df44ba2db0fffdbe11dfea",
    "id": "CVE-2026-53198",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\nLinux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\nLinux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\nLinux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\nLinux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\nLinux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\nLinux Linux 0\nLinux Linux 0\nLinux Linux 0\nLinux Linux 0\nLinux Linux 0",
    "sourceHref": "",
    "cvss": {
        "score": 8.8,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
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        "baseScore": 0,
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        "cvssV3": {
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    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
    "vendor": "Linux",
    "ai_description": "AI processing failed - invalid JSON response",
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    "ai_score": 0
}