CVE-2026-97556

smb: client: avoid leaking refcount when cifs_sb_tlink() fails

State: Published
Severity: Not scored
Published: Sep 25, 2026
Updated: Oct 30, 2026
Reserved: Sep 24, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

smb: client: avoid leaking refcount when cifs_sb_tlink() fails

cifs_oplock_break() takes over the reference that cifs_queue_oplock_break() acquired when it queued the work, and drops it with _cifsFileInfo_put() once the break has been processed.

Only in setups with "-o multiuser", cifs_sb_tlink() may fail, at which point cifs_oplock_break() returns without putting the file reference, mirroring the reference leak we already fixed in the companion patch to cifs_queue_oplock_break().

This would trigger a crash due to busy inodes on the next unmount:

BUG: Dentry ... still in use (1) [unmount of cifs cifs] VFS: Busy inodes after unmount of cifs (cifs)

Drop the reference on that path as well. Doing so before the out label mirrors the normal path, which also puts the reference before cifs_done_oplock_break().

Found by Sashiko code review. The failure path was not exercised at runtime.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	b99f490ea87ebcca3a429fd8837067feb56a4c7c to before f1fd8a84181b3af03c508e0b02b4877945dd070aAffected 5ee28bcfbaacf289eb25c662a2862542ea6ce6a7 to before 55c5f095d4df14271b238f826e1392fda7b6e60eAffected e8f5f849ffce24490eb9449e98312b66c0dba76f to before e9c5bcc88b8337157e480c85a6d2f326bc265012Affected e8f5f849ffce24490eb9449e98312b66c0dba76f to before 9ec991e148368e3207e98134c509a625097f7693Affected e8f5f849ffce24490eb9449e98312b66c0dba76f to before dd03fd658ea59821505e0e643b6b7cbdf51c4e1dAffected e8f5f849ffce24490eb9449e98312b66c0dba76f to before 1d1b0f1d812a4011a57bc6c70492c34a2e46c6ddAffected e8f5f849ffce24490eb9449e98312b66c0dba76f to before 23b26f4408ac3f35a482d2e5cf6fc865d4201b71Affected 6b67a6d2e50634fe127e656147c81915955e9f5eAffected 5.15.128 to before 5.15.224Affected 6.1.47 to before 6.1.189Affected 6.4.12 to before 6.5Affected
LinuxLinux	6.5Affected before 6.5Not affected 5.15.224 through 5.15.Not affected 6.1.189 through 6.1.Not affected 6.6.158 through 6.6.Not affected 6.12.111 through 6.12.Not affected 6.18.53 through 6.18.Not affected 7.2.7 through 7.2.Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

b99f490ea87ebcca3a429fd8837067feb56a4c7c to before f1fd8a84181b3af03c508e0b02b4877945dd070aAffected
5ee28bcfbaacf289eb25c662a2862542ea6ce6a7 to before 55c5f095d4df14271b238f826e1392fda7b6e60eAffected
e8f5f849ffce24490eb9449e98312b66c0dba76f to before e9c5bcc88b8337157e480c85a6d2f326bc265012Affected
e8f5f849ffce24490eb9449e98312b66c0dba76f to before 9ec991e148368e3207e98134c509a625097f7693Affected
e8f5f849ffce24490eb9449e98312b66c0dba76f to before dd03fd658ea59821505e0e643b6b7cbdf51c4e1dAffected
e8f5f849ffce24490eb9449e98312b66c0dba76f to before 1d1b0f1d812a4011a57bc6c70492c34a2e46c6ddAffected
e8f5f849ffce24490eb9449e98312b66c0dba76f to before 23b26f4408ac3f35a482d2e5cf6fc865d4201b71Affected
6b67a6d2e50634fe127e656147c81915955e9f5eAffected
5.15.128 to before 5.15.224Affected
6.1.47 to before 6.1.189Affected
6.4.12 to before 6.5Affected

LinuxLinux

6.5Affected
before 6.5Not affected
5.15.224 through 5.15.*Not affected
6.1.189 through 6.1.*Not affected
6.6.158 through 6.6.*Not affected
6.12.111 through 6.12.*Not affected
6.18.53 through 6.18.*Not affected
7.2.7 through 7.2.*Not affected
7.3 and laterNot affected

References

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.