nfsd: close shrinker/GC/fsnotify vs per-net shutdown race in filecache
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.12.111, 6.18.51, 7.2.4
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: close shrinker/GC/fsnotify vs per-net shutdown race in filecache The shrinker, GC worker, and fsnotify/lease callbacks can unhash an nfsd_file from the rhashtable and then call nfsd_file_dispose_list_delayed() to move it to the per-net dispose list. If nfsd_file_cache_shutdown_net() runs concurrently, its rhashtable walk misses the already-unhashed file, and its drain of the per-net dispose list can run before the file has been queued. The file then sits on the per-net list with no thread to drain it, leaking both the file and its associated state. The GC worker and shrinker already hold nfsd_gc_lock while walking the LRU, but in the original code they release it before calling nfsd_file_dispose_list_delayed(). The fsnotify/lease path (nfsd_file_close_inode) has no synchronization at all. Fix this by: 1. Widening nfsd_gc_lock in both nfsd_file_gc() and nfsd_file_lru_scan() to cover the nfsd_file_dispose_list_delayed() call. 2. Wrapping nfsd_file_close_inode() in nfsd_gc_lock so that all three callers of nfsd_file_dispose_list_delayed() hold the lock. 3. Adding a spin_lock/unlock(nfsd_gc_lock) barrier in nfsd_file_cache_shutdown_net() after the purge, so that any in-progress disposal has fully completed before the per-net list is drained. All operations inside the lock are non-sleeping (rhashtable lookups, atomic bit/refcount ops, list moves, svc_wake_up), so the spinlock is appropriate.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From ffb402596147ac583f3464ff5c48feb9423e3838 · fixed in b15997b53b61c74fb4d083f7261d19f389ff854f; From ffb402596147ac583f3464ff5c48feb9423e3838 · fixed in 6d6b9f6a75c3767250e9c23ace4e384ab8f7843e; From ffb402596147ac583f3464ff5c48feb9423e3838 · fixed in 08af9593e2b472fd98c00faf1bf03bdbb7203477; From ffb402596147ac583f3464ff5c48feb9423e3838 · fixed in 40162cfea79b9510380decfdd1795b754dc9f972
- Linux Linux
6.9
- KernelLinux
From 6.9.0 · fixed in 6.12.111; From 6.13.0 · fixed in 6.18.51; From 6.19.0 · fixed in 7.2.4