[PATCH 5.16 204/285] io_uring: dont touch scm_fp_list after queueing skb

Greg Kroah-Hartman
2022-04-12T08:40:39Z

From: Pavel Begunkov <asml.silence@gmail.com>

[ 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>
---
fs/io_uring.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index c744b9910d9e..d4db0b911896 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8176,8 +8176,12 @@ 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);
--
2.35.1