There is a race condition leading to a kernel crash from a null
dereference when attemping to access fc->lock in
fuse_uring_create_queue(). fc may be NULL in the case where another
thread is creating the uring in fuse_uring_create() and has set
fc->ring but has not yet set ring->fc when fuse_uring_create_queue()
reads ring->fc.
This fix sets fc->ring only after ring->fc has been set, which
guarantees now that ring->fc is a proper pointer when any queues are
created.
Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
Fixes: 24fe962c86f5 ("fuse: {io-uring} Handle SQEs - register commands")
---
fs/fuse/dev_uring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index ab8c26042aa8..618a413ef400 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -235,9 +235,9 @@ static struct fuse_ring *fuse_uring_create(struct fuse_conn *fc)
init_waitqueue_head(&ring->stop_waitq);
- fc->ring = ring;
ring->nr_queues = nr_queues;
ring->fc = fc;
+ fc->ring = ring;
ring->max_payload_sz = max_payload_size;
atomic_set(&ring->queue_refs, 0);
--
2.47.1
