CVE-2025-40237

Name of the Vulnerable Software and Affected Versions Linux kernel versions prior to 6.17.0-rc6

Description The Linux kernel contains a flaw within the fs/notify subsystem. Specifically, calling inotify show fdinfo() on a file descriptor watching an overlayfs inode during unmounting can lead to a dereference of a NULL pointer. This occurs when exportfs encode fid() is called with s umount, potentially causing a general protection fault. The issue arises because ovl check encode origin dereferences inode->i sb->s root after it has been set to NULL during the unmount process. The fix involves protecting calls to exportfs encode fid() from show mark fhandle() using the s umount lock.

Recommendations Update to a version newer than 6.17.0-rc6.