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Subject[PATCH 4.9 076/107] fuse: fix unlocked access to processing queue
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Miklos Szeredi <mszeredi@redhat.com>

commit 45ff350bbd9d0f0977ff270a0d427c71520c0c37 upstream.

fuse_dev_release() assumes that it's the only one referencing the
fpq->processing list, but that's not true, since fuse_abort_conn() can be
doing the same without any serialization between the two.

Fixes: c3696046beb3 ("fuse: separate pqueue for clones")
Cc: <stable@vger.kernel.org> # v4.2
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/fuse/dev.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -2142,9 +2142,15 @@ int fuse_dev_release(struct inode *inode
if (fud) {
struct fuse_conn *fc = fud->fc;
struct fuse_pqueue *fpq = &fud->pq;
+ LIST_HEAD(to_end);

+ spin_lock(&fpq->lock);
WARN_ON(!list_empty(&fpq->io));
- end_requests(fc, &fpq->processing);
+ list_splice_init(&fpq->processing, &to_end);
+ spin_unlock(&fpq->lock);
+
+ end_requests(fc, &to_end);
+
/* Are we the last open device? */
if (atomic_dec_and_test(&fc->dev_count)) {
WARN_ON(fc->iq.fasync != NULL);

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