CVE-2026-31400

In the Linux kernel, the following vulnerability has been resolved:

sunrpc: fix cacherequest leak in cacherelease

When a reader's file descriptor is closed while in the middle of reading a cacherequest (rp->offset != 0), cacherelease() decrements the request's readers count but never checks whether it should free the request.

In cacheread(), when readers drops to 0 and CACHEPENDING is clear, the cacherequest is removed from the queue and freed along with its buffer and cachehead reference. cache_release() lacks this cleanup.

The only other path that frees requests with readers == 0 is cachedequeue(), but it runs only when CACHEPENDING transitions from set to clear. If that transition already happened while readers was still non-zero, cache_dequeue() will have skipped the request, and no subsequent call will clean it up.

Add the same cleanup logic from cacheread() to cacherelease(): after decrementing readers, check if it reached 0 with CACHEPENDING clear, and if so, dequeue and free the cacherequest.