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nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net nfsd_file_dispose_list_delayed() defers fput() to nfsd service threads via a per-net freeme queue, preventing the shrinker and GC worker from bearing the cost of closing files (see ffb402596147). However, the queue lives in a separately-allocated struct nfsd_fcache_disposal that is freed by nfsd_free_fcache_disposal_net() during per-net teardown. The global shrinker, laundrette, and fsnotify callbacks can still be inside nfsd_file_dispose_list_delayed() dereferencing that pointer, causing a use-after-free. Inline the spinlock and freeme list directly into struct nfsd_net (as fcache_dispose_lock and fcache_dispose_list), eliminating the separately allocated struct nfsd_fcache_disposal entirely. These fields now have the same lifetime as the net namespace itself, so there is no dangling pointer to chase. nfsd_file_cache_start_net() now just initializes the inline fields and cannot fail due to allocation. nfsd_file_cache_shutdown_net() drains the inline list directly instead of freeing a separate struct. The alloc/free helpers are removed.
References
Affected products
- <5.11
- <ba0ee9e04b7a0356c28d5a2fe445db675d24e572
- <cadc9036d5a8209f89e7026ddba7cfb1c716b03c
- ==e8f923e1e9fcc0832a12c8a2461792e5a9544c03
- <5.17
- =<7.2.*
- <bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4
- ==3bc94fb44f10ef852723e1aeaac6794c5ab16aec
- ==5.17
- <5.16
- =<6.18.*
- =<*