Description
In the Linux kernel, the following vulnerability has been resolved: vfs: Don't leak disconnected dentries on umount When user calls open_by_handle_at() on some inode that is not cached, we will create disconnected dentry for it. If such dentry is a directory, exportfs_decode_fh_raw() will then try to connect this dentry to the dentry tree through reconnect_path(). It may happen for various reasons (such as corrupted fs or race with rename) that the call to lookup_one_unlocked() in reconnect_one() will fail to find the dentry we are trying to reconnect and instead create a new dentry under the parent. Now this dentry will not be marked as disconnected although the parent still may well be disconnected (at least in case this inconsistency happened because the fs is corrupted and .. doesn't point to the real parent directory). This creates inconsistency in disconnected flags but AFAICS it was mostly harmless. At least until commit f1ee616214cb ("VFS: don't keep disconnected dentries on d_anon") which removed adding of most disconnected dentries to sb->s_anon list. Thus after this commit cleanup of disconnected dentries implicitely relies on the fact that dput() will immediately reclaim such dentries. However when some leaf dentry isn't marked as disconnected, as in the scenario described above, the reclaim doesn't happen and the dentries are "leaked". Memory reclaim can eventually reclaim them but otherwise they stay in memory and if umount comes first, we hit infamous "Busy inodes after unmount" bug. Make sure all dentries created under a disconnected parent are marked as disconnected as well.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
f1ee616214cb22410e939d963bbb2349c2570f02 to < b5abafd0aa8d7bcb935c8f91e4cfc2f2820759e4affectedf1ee616214cb22410e939d963bbb2349c2570f02 to < 20863bb7fbb016379f8227122edfabc5c799bc79affectedf1ee616214cb22410e939d963bbb2349c2570f02 to < 8004d4b8cbf1bd68a23c160d57287e177c82cc69affectedf1ee616214cb22410e939d963bbb2349c2570f02 to < 7e0c8aaf4e28918abded547a5147c7d52c4af7d2affectedf1ee616214cb22410e939d963bbb2349c2570f02 to < cebfbf40056a4d858b2a3ca59a69936d599bd209affectedf1ee616214cb22410e939d963bbb2349c2570f02 to < 620f3b0ede9c5cb4976cd0457d0b04ad551e5d6baffectedf1ee616214cb22410e939d963bbb2349c2570f02 to < eadc49999fa994d6fbd70c332bd5d5051cc42261affectedf1ee616214cb22410e939d963bbb2349c2570f02 to < 56094ad3eaa21e6621396cc33811d8f72847a834affected
Linux Linux
Default version status: affected
4.16affected0 to < 4.16unaffected5.4.301 to ≤ 5.4.*unaffected5.10.246 to ≤ 5.10.*unaffected5.15.196 to ≤ 5.15.*unaffected6.1.158 to ≤ 6.1.*unaffected6.6.114 to ≤ 6.6.*unaffected6.12.55 to ≤ 6.12.*unaffected6.17.5 to ≤ 6.17.*unaffected6.18 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/b5abafd0aa8d7bcb935c8f91e4cfc2f2820759e4 ↗
- https://git.kernel.org/stable/c/20863bb7fbb016379f8227122edfabc5c799bc79 ↗
- https://git.kernel.org/stable/c/8004d4b8cbf1bd68a23c160d57287e177c82cc69 ↗
- https://git.kernel.org/stable/c/7e0c8aaf4e28918abded547a5147c7d52c4af7d2 ↗
- https://git.kernel.org/stable/c/cebfbf40056a4d858b2a3ca59a69936d599bd209 ↗
- https://git.kernel.org/stable/c/620f3b0ede9c5cb4976cd0457d0b04ad551e5d6b ↗
- https://git.kernel.org/stable/c/eadc49999fa994d6fbd70c332bd5d5051cc42261 ↗
- https://git.kernel.org/stable/c/56094ad3eaa21e6621396cc33811d8f72847a834 ↗
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html ↗
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html ↗