CVE-2021-46972
Description
In the Linux kernel, the following vulnerability has been resolved: ovl: fix leaked dentry Since commit 6815f479ca90 ("ovl: use only uppermetacopy state in ovl_lookup()"), overlayfs doesn't put temporary dentry when there is a metacopy error, which leads to dentry leaks when shutting down the related superblock: overlayfs: refusing to follow metacopy origin for (/file0) ... BUG: Dentry (____ptrval____){i=3f33,n=file3} still in use (1) [unmount of overlay overlay] ... WARNING: CPU: 1 PID: 432 at umount_check.cold+0x107/0x14d CPU: 1 PID: 432 Comm: unmount-overlay Not tainted 5.12.0-rc5 #1 ... RIP: 0010:umount_check.cold+0x107/0x14d ... Call Trace: d_walk+0x28c/0x950 ? dentry_lru_isolate+0x2b0/0x2b0 ? __kasan_slab_free+0x12/0x20 do_one_tree+0x33/0x60 shrink_dcache_for_umount+0x78/0x1d0 generic_shutdown_super+0x70/0x440 kill_anon_super+0x3e/0x70 deactivate_locked_super+0xc4/0x160 deactivate_super+0xfa/0x140 cleanup_mnt+0x22e/0x370 __cleanup_mnt+0x1a/0x30 task_work_run+0x139/0x210 do_exit+0xb0c/0x2820 ? __kasan_check_read+0x1d/0x30 ? find_held_lock+0x35/0x160 ? lock_release+0x1b6/0x660 ? mm_update_next_owner+0xa20/0xa20 ? reacquire_held_locks+0x3f0/0x3f0 ? __sanitizer_cov_trace_const_cmp4+0x22/0x30 do_group_exit+0x135/0x380 __do_sys_exit_group.isra.0+0x20/0x20 __x64_sys_exit_group+0x3c/0x50 do_syscall_64+0x45/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xae ... VFS: Busy inodes after unmount of overlay. Self-destruct in 5 seconds. Have a nice day... This fix has been tested with a syzkaller reproducer.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No vendor mitigations ingested yet for this CVE. The mitigation-content worker queues fetches as references arrive — check back in a few minutes, or see the references list below.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| rocky | 8 | fixed | |
| sles | affected | | |
| debian | bookworm | fixed | 5.10.38-1 |
| debian | bullseye | fixed | 5.10.38-1 |
| debian | forky | fixed | 5.10.38-1 |
| debian | sid | fixed | 5.10.38-1 |
| debian | trixie | fixed | 5.10.38-1 |
| almalinux | 8 | fixed | kernel-rt-core-4.18.0-553.8.1.rt7.349.el8_10.x86_64.rpm |
References
- https://errata.rockylinux.org/RXSA-2024:4211
- https://errata.rockylinux.org/RLSA-2024:4352
- https://errata.rockylinux.org/RLSA-2024:4211
- https://www.suse.com/security/cve/CVE-2021-46972.html
- https://security-tracker.debian.org/tracker/CVE-2021-46972
- https://access.redhat.com/errata/RHSA-2024:4211
- https://bugzilla.redhat.com/1918601
- https://bugzilla.redhat.com/2248122
- https://bugzilla.redhat.com/2258875
- https://bugzilla.redhat.com/2265517
- https://bugzilla.redhat.com/2265519
- https://bugzilla.redhat.com/2265520
- https://bugzilla.redhat.com/2265800
- https://bugzilla.redhat.com/2266408
- https://bugzilla.redhat.com/2266831
- https://bugzilla.redhat.com/2267513
- https://bugzilla.redhat.com/2267518
- https://bugzilla.redhat.com/2267730
- https://bugzilla.redhat.com/2270093
- https://bugzilla.redhat.com/2271680
- https://bugzilla.redhat.com/2272692
- https://bugzilla.redhat.com/2272829
- https://bugzilla.redhat.com/2273204
- https://bugzilla.redhat.com/2273278
- https://bugzilla.redhat.com/2273423
💬 Discuss CVE-2021-46972 on VIR Community →
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.