CVE-2025-38527

smb: client: fix use-after-free in cifs_oplock_break

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix use-after-free in cifs_oplock_break A race condition can occur in cifs_oplock_break() leading to a use-after-free of the cinode structure when unmounting: cifs_oplock_break() _cifsFileInfo_put(cfile) cifsFileInfo_put_final() cifs_sb_deactive() [last ref, start releasing sb] kill_sb() kill_anon_super() generic_shutdown_super() evict_inodes() dispose_list() evict() destroy_inode() call_rcu(&inode->i_rcu, i_callback) spin_lock(&cinode->open_file_lock) <- OK [later] i_callback() cifs_free_inode() kmem_cache_free(cinode) spin_unlock(&cinode->open_file_lock) <- UAF cifs_done_oplock_break(cinode) <- UAF The issue occurs when umount has already released its reference to the superblock. When _cifsFileInfo_put() calls cifs_sb_deactive(), this releases the last reference, triggering the immediate cleanup of all inodes under RCU. However, cifs_oplock_break() continues to access the cinode after this point, resulting in use-after-free. Fix this by holding an extra reference to the superblock during the entire oplock break operation. This ensures that the superblock and its inodes remain valid until the oplock break completes.

N/A
CVSS
Severity:
EPSS 0.02%
Affected: Linux Linux
Affected: Linux Linux
Published at:
Updated at:

References

Frequently Asked Questions

What is the severity of CVE-2025-38527?
CVE-2025-38527 has not yet been assigned a CVSS score.
How to fix CVE-2025-38527?
To fix CVE-2025-38527, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2025-38527 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-38527 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-38527?
CVE-2025-38527 affects Linux Linux, Linux Linux.
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