io_uring: don't touch scm_fp_list after queueing skb
[ Upstream commit a07211e3001435fe8591b992464cd8d5e3c98c5a ]
It's safer to not touch scm_fp_list after we queued an skb to which it
was assigned, there might be races lurking if we screw subtle sync
guarantees on the io_uring side.
Fixes: 6b06314c47e14 ("io_uring: add file set registration")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 21823d1..2faa558 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8126,8 +8126,12 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
refcount_add(skb->truesize, &sk->sk_wmem_alloc);
skb_queue_head(&sk->sk_receive_queue, skb);
- for (i = 0; i < nr_files; i++)
- fput(fpl->fp[i]);
+ for (i = 0; i < nr; i++) {
+ struct file *file = io_file_from_index(ctx, i + offset);
+
+ if (file)
+ fput(file);
+ }
} else {
kfree_skb(skb);
free_uid(fpl->user);