[PATCH 5.15 197/570] sunrpc: fix cache_request leak in cache_release

Greg Kroah-Hartman
2026-04-13T16:27:56Z

From: Jeff Layton <jlayton@kernel.org>

commit 17ad31b3a43b72aec3a3d83605891e1397d0d065 upstream.

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

In cache_read(), when readers drops to 0 and CACHE_PENDING is clear, the
cache_request is removed from the queue and freed along with its buffer
and cache_head reference. cache_release() lacks this cleanup.

The only other path that frees requests with readers == 0 is
cache_dequeue(), but it runs only when CACHE_PENDING 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 cache_read() to cache_release(): after
decrementing readers, check if it reached 0 with CACHE_PENDING clear,
and if so, dequeue and free the cache_request.

Reported-by: NeilBrown <neilb@ownmail.net>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@kernel.org
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sunrpc/cache.c | 26 +++++++++++++++++++++-----
1 file changed, 21 insertions(+), 5 deletions(-)

--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -1037,14 +1037,25 @@ static int cache_release(struct inode *i
struct cache_reader *rp = filp->private_data;

if (rp) {
+ struct cache_request *rq = NULL;
+
spin_lock(&queue_lock);
if (rp->offset) {
struct cache_queue *cq;
- for (cq= &rp->q; &cq->list != &cd->queue;
- cq = list_entry(cq->list.next, struct cache_queue, list))
+ for (cq = &rp->q; &cq->list != &cd->queue;
+ cq = list_entry(cq->list.next,
+ struct cache_queue, list))
if (!cq->reader) {
- container_of(cq, struct cache_request, q)
- ->readers--;
+ struct cache_request *cr =
+ container_of(cq,
+ struct cache_request, q);
+ cr->readers--;
+ if (cr->readers == 0 &&
+ !test_bit(CACHE_PENDING,
+ &cr->item->flags)) {
+ list_del(&cr->q.list);
+ rq = cr;
+ }
break;
}
rp->offset = 0;
@@ -1052,9 +1063,14 @@ static int cache_release(struct inode *i
list_del(&rp->q.list);
spin_unlock(&queue_lock);

+ if (rq) {
+ cache_put(rq->item, cd);
+ kfree(rq->buf);
+ kfree(rq);
+ }
+
filp->private_data = NULL;
kfree(rp);
-
}
if (filp->f_mode & FMODE_WRITE) {
atomic_dec(&cd->writers);