Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: cifs: Fix busy dentry used after unmounting Since commit 340cea84f691c ("cifs: open files should not hold ref on superblock"), cifs file only holds the dentry ref_cnt, the cifs file close work(cfile->deferred) could be executed after unmounting, which will trigger a warning in generic_shutdown_super: BUG: Dentry 00000000a14a6845{i=c,n=file} still in use (1) [unmount of cifs cifs] The detailed processs is: process A process B kworker fd = open(PATH) vfs_open file->__f_path = *path // dentry->d_lockref.count = 1 cifs_open cifs_new_fileinfo cfile->dentry = dget(dentry) // dentry->d_lockref.count = 2 close(fd) __fput cifs_close queue_delayed_work(deferredclose_wq, cfile->deferred) dput(dentry) // dentry->d_lockref.count = 1 smb2_deferred_work_close _cifsFileInfo_put list_del(&cifs_file->flist) umount cleanup_mnt deactivate_super cifs_kill_sb cifs_close_all_deferred_files_sb cifs_close_all_deferred_files // cannot find cfile, skip _cifsFileInfo_put kill_anon_super generic_shutdown_super shrink_dcache_for_umount umount_check WARN ! // dentry->d_lockref.count = 1 cifsFileInfo_put_final dput(cifs_file->dentry) // dentry->d_lockref.count = 0 Fix it by flushing 'deferredclose_wq' before calling kill_anon_super. Fetch a reproducer in https://bugzilla.kernel.org/show_bug.cgi?id=221548.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 708c276f516d27beaded7f372ac8111cee43926c before c7364cea52531534676b9f7dbc0a477c11f4c050; affected 0629a1a187e424373364d681b42b101894bdb548 before bdc349a87f1fb02c18c4071858a06542bfea783d; affected 0e4b8faaaebe3137bec5723ef2b3cb0437fb38fd before f2deaa2f409a4598eaa10f2a93a676c0632af248; affected f655467a9973f964b267871e5fef533ad5014494 before 5e7d9d0805e58fa3760894e73115b7a74024fd07; affected 340cea84f691c5206561bb2e0147158fe02070be before e1ffa6cf662383f95816eed1b623429d82675e75; affected 340cea84f691c5206561bb2e0147158fe02070be before c68337442f03953237a94577beb468ab2662a851; affected 30afc6ea72cc6cf7c8d579e79b64232801c38d08; affected 6.1.167 before 6.1.175; affected 6.6.130 before 6.6.142; affected 6.12.78 before 6.12.92; affected 6.18.20 before 6.18.34; affected 6.19.10 before 6.20 |
| Linux / Linux | affected 7.0; unaffected 0 before 7.0; unaffected 6.1.175 through 6.1.*; unaffected 6.6.142 through 6.6.*; unaffected 6.12.92 through 6.12.*; unaffected 6.18.34 through 6.18.*; unaffected 7.0.11 through 7.0.*; unaffected 7.1 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/c7364cea52531534676b9f7dbc0a477c11f4c050
- https://git.kernel.org/stable/c/bdc349a87f1fb02c18c4071858a06542bfea783d
- https://git.kernel.org/stable/c/f2deaa2f409a4598eaa10f2a93a676c0632af248
- https://git.kernel.org/stable/c/5e7d9d0805e58fa3760894e73115b7a74024fd07
- https://git.kernel.org/stable/c/e1ffa6cf662383f95816eed1b623429d82675e75
- https://git.kernel.org/stable/c/c68337442f03953237a94577beb468ab2662a851