Linux vulnerability

What happened

In the Linux kernel, the following vulnerability has been resolved: inotify: fix watch count leak when fsnotify_add_inode_mark_locked() fails When fsnotify_add_inode_mark_locked() fails in inotify_new_watch(), the error path calls inotify_remove_from_idr() but does not call dec_inotify_watches() to undo the preceding inc_inotify_watches(). This leaks a watch count, and repeated failures can exhaust the max_user_watches limit with -ENOSPC even when no watches are active. Prior to commit 1cce1eea0aff ("inotify: Convert to using per-namespace limits"), the watch count was incremented after fsnotify_add_mark_locked() succeeded, so this path was not affected. The conversion moved inc_inotify_watches() before the mark insertion without adding the corresponding rollback. Add the missing dec_inotify_watches() call in the error path.

Affected versions

Linux: 1cce1eea0aff51201753fcaca421df825b0813b6 through before 3ab58cf42c46bf2366d2f55ae5c59299d5e178b7 (git); 1cce1eea0aff51201753fcaca421df825b0813b6 through before 10edf7e0ffdc7faa18e2244b17722c1b882b8273 (git); 1cce1eea0aff51201753fcaca421df825b0813b6 through before 3ad9ccea1b25435f6179b57aa891960beb7ce8f9 (git); 1cce1eea0aff51201753fcaca421df825b0813b6 through before 8bcc1cd237ab5ccfdd102869fa031c541943cf40 (git); 1cce1eea0aff51201753fcaca421df825b0813b6 through before 73ddc8518a32baff6bc17afda4ee1ebae5b4ed12 (git); 1cce1eea0aff51201753fcaca421df825b0813b6 through before fdaa42ca370d056428e5e171247c8fdce8dff36a (git); 1cce1eea0aff51201753fcaca421df825b0813b6 through before 9e48844f708eb48bae4e79cb21edc097c966306d (git); 1cce1eea0aff51201753fcaca421df825b0813b6 through before 6a320935fa4293e9e599ec9f85dc9eb3be7029f8 (git); 4.11; V3.1.6 through before * (custom) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.