CVE-2026-46040inotify: fix watch count leak when fsnotify_add_inode_mark_locked() fails

Official description

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 packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/3ab58cf42c46bf2366d2f55ae5c59299d5e178b7
• https://git.kernel.org/stable/c/10edf7e0ffdc7faa18e2244b17722c1b882b8273
• https://git.kernel.org/stable/c/3ad9ccea1b25435f6179b57aa891960beb7ce8f9
• https://git.kernel.org/stable/c/8bcc1cd237ab5ccfdd102869fa031c541943cf40
• https://git.kernel.org/stable/c/73ddc8518a32baff6bc17afda4ee1ebae5b4ed12
• https://git.kernel.org/stable/c/fdaa42ca370d056428e5e171247c8fdce8dff36a
• https://git.kernel.org/stable/c/9e48844f708eb48bae4e79cb21edc097c966306d
• https://git.kernel.org/stable/c/6a320935fa4293e9e599ec9f85dc9eb3be7029f8
• https://cert-portal.siemens.com/productcert/html/ssa-019113.html
• https://cert-portal.siemens.com/productcert/html/ssa-457936.html
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html