Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free of a deferred file_lock on double SMB2_CANCEL A deferred byte-range lock (an SMB2_LOCK that blocks) registers an async work on conn->async_requests via setup_async_work(), with cancel_fn = smb2_remove_blocked_lock and cancel_argv[0] pointing at the struct file_lock. When the request is cancelled, the worker frees the file_lock with locks_free_lock() and takes the cancelled early-exit, which "goto out"s and never reaches release_async_work() -- the only site that unlinks the work from conn->async_requests and clears cancel_fn/cancel_argv. The work therefore stays matchable on async_requests with a live cancel_fn pointing at the freed file_lock, until connection teardown finally runs release_async_work(). smb2_cancel() fires cancel_fn unconditionally with no state guard, so a second SMB2_CANCEL for the same AsyncId, arriving in that window, re-runs smb2_remove_blocked_lock() on the freed file_lock -- a slab use-after-free: BUG: KASAN: slab-use-after-free in __locks_delete_block __locks_delete_block locks_delete_block ksmbd_vfs_posix_lock_unblock smb2_remove_blocked_lock smb2_cancel <- 2nd SMB2_CANCEL fires cancel_fn handle_ksmbd_work Allocated by ...: locks_alloc_lock <- smb2_lock Freed by ...: locks_free_lock <- smb2_lock (cancelled branch) ... cache file_lock_cache of size 192 Reproduced on mainline with KASAN by an authenticated SMB client. Skip a work whose state is already KSMBD_WORK_CANCELLED so its cancel callback cannot be fired a second time.
CVSS breakdown
Affected products
- Linux / Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – b7063c7426ea5a4d15e01b60538718765392f49d
- Linux / Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – 0da2e073f9cbf4985a0fd9acb71bc5ff599f8afd
- Linux / Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – 89ae9df09d2c1fb4a4eb495c113a7ce1dca34147
- Linux / Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – 14d2eee0193ac3cd1bf3d014373449f0b8d35d6d
- Linux / Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – 2b2eda2821cff1d1b5a423b6ee7d8fc6fbc8e694
- Linux / Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – f580d27e8928828693df44ba2db0fffdbe11dfea
- Linux / Linux0 – 6.1.176
- Linux / Linux0 – 6.6.143
- Linux / Linux0 – 6.12.94
- Linux / Linux0 – 6.18.36
- Linux / Linux0 – 7.0.13
- Linux / Linux6.1.176 – 6.1.*
- Linux / Linux6.6.143 – 6.6.*
- Linux / Linux6.12.94 – 6.12.*
- Linux / Linux6.18.36 – 6.18.*
- Linux / Linux7.0.13 – 7.0.*
- Linux / Linux7.1 – *
References
- MISChttps://git.kernel.org/stable/c/b7063c7426ea5a4d15e01b60538718765392f49d
- MISChttps://git.kernel.org/stable/c/0da2e073f9cbf4985a0fd9acb71bc5ff599f8afd
- MISChttps://git.kernel.org/stable/c/89ae9df09d2c1fb4a4eb495c113a7ce1dca34147
- MISChttps://git.kernel.org/stable/c/14d2eee0193ac3cd1bf3d014373449f0b8d35d6d
- MISChttps://git.kernel.org/stable/c/2b2eda2821cff1d1b5a423b6ee7d8fc6fbc8e694
- MISChttps://git.kernel.org/stable/c/f580d27e8928828693df44ba2db0fffdbe11dfea