[PATCH 1/2] fuse: missing copy_finish in fuse-over-io-uring argument copies

[Bernd Schubert <bschubert@ddn.com>]

From: Cheng Ding <cding@ddn.com>

Fix a possible reference count leak of payload pages during
fuse argument copies.

Fixes: c090c8abae4b ("fuse: Add io-uring sqe commit and fetch support")
Cc: <stable@vger.kernel.org> # v6.14
Signed-off-by: Cheng Ding <cding@ddn.com>
Signed-off-by: Bernd Schubert <bschubert@ddn.com>
---
 fs/fuse/dev.c        |  2 +-
 fs/fuse/dev_uring.c  | 12 +++++++++---
 fs/fuse/fuse_dev_i.h |  1 +
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 132f38619d70720ce74eedc002a7b8f31e760a61..49b18d7accb39927e49bc3814ad2c3e51db84bb4 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -846,7 +846,7 @@ void fuse_copy_init(struct fuse_copy_state *cs, bool write,
 }
 
 /* Unmap and put previous page of userspace buffer */
-static void fuse_copy_finish(struct fuse_copy_state *cs)
+void fuse_copy_finish(struct fuse_copy_state *cs)
 {
 	if (cs->currbuf) {
 		struct pipe_buffer *buf = cs->currbuf;
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index f6b12aebb8bbe7d255980593b75b5fb5af9c669e..3721c2d91627f5438b6997df3de63734704e56ff 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -598,7 +598,9 @@ static int fuse_uring_copy_from_ring(struct fuse_ring *ring,
 	cs.is_uring = true;
 	cs.req = req;
 
-	return fuse_copy_out_args(&cs, args, ring_in_out.payload_sz);
+	err = fuse_copy_out_args(&cs, args, ring_in_out.payload_sz);
+	fuse_copy_finish(&cs);
+	return err;
 }
 
  /*
@@ -651,13 +653,17 @@ static int fuse_uring_args_to_ring(struct fuse_ring *ring, struct fuse_req *req,
 			     (struct fuse_arg *)in_args, 0);
 	if (err) {
 		pr_info_ratelimited("%s fuse_copy_args failed\n", __func__);
-		return err;
+		goto copy_finish;
 	}
 
 	ent_in_out.payload_sz = cs.ring.copied_sz;
 	err = copy_to_user(&ent->headers->ring_ent_in_out, &ent_in_out,
 			   sizeof(ent_in_out));
-	return err ? -EFAULT : 0;
+	if (err)
+		err = -EFAULT;
+copy_finish:
+	fuse_copy_finish(&cs);
+	return err;
 }
 
 static int fuse_uring_copy_to_ring(struct fuse_ring_ent *ent,
diff --git a/fs/fuse/fuse_dev_i.h b/fs/fuse/fuse_dev_i.h
index 6e8373f970409e83efdc5d5cfc3d943a8948d3a7..134bf44aff0d39ae8d5d47cf1518efcf2f1cfc23 100644
--- a/fs/fuse/fuse_dev_i.h
+++ b/fs/fuse/fuse_dev_i.h
@@ -62,6 +62,7 @@ void fuse_dev_end_requests(struct list_head *head);
 
 void fuse_copy_init(struct fuse_copy_state *cs, bool write,
 			   struct iov_iter *iter);
+void fuse_copy_finish(struct fuse_copy_state *cs);
 int fuse_copy_args(struct fuse_copy_state *cs, unsigned int numargs,
 		   unsigned int argpages, struct fuse_arg *args,
 		   int zeroing);

-- 
2.43.0