[PATCH 1/2] io_uring: fix list corruption for splice file_get

[Pavel Begunkov <asml.silence@gmail.com>]

kernel BUG at lib/list_debug.c:29!
Call Trace:
 __list_add include/linux/list.h:67 [inline]
 list_add include/linux/list.h:86 [inline]
 io_file_get+0x8cc/0xdb0 fs/io_uring.c:6466
 __io_splice_prep+0x1bc/0x530 fs/io_uring.c:3866
 io_splice_prep fs/io_uring.c:3920 [inline]
 io_req_prep+0x3546/0x4e80 fs/io_uring.c:6081
 io_queue_sqe+0x609/0x10d0 fs/io_uring.c:6628
 io_submit_sqe fs/io_uring.c:6705 [inline]
 io_submit_sqes+0x1495/0x2720 fs/io_uring.c:6953
 __do_sys_io_uring_enter+0x107d/0x1f30 fs/io_uring.c:9353
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

io_file_get() may be called from splice, and so REQ_F_INFLIGHT may
already be set.

Fixes: 02a13674fa0e8 ("io_uring: account io_uring internal files as REQ_F_INFLIGHT")
Cc: stable@vger.kernel.org # 5.9+
Reported-by: syzbot+6879187cf57845801267@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index ae388cc52843..39ae1f821cef 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6460,7 +6460,8 @@ static struct file *io_file_get(struct io_submit_state *state,
 		file = __io_file_get(state, fd);
 	}
 
-	if (file && file->f_op == &io_uring_fops) {
+	if (file && file->f_op == &io_uring_fops &&
+	    !(req->flags & REQ_F_INFLIGHT)) {
 		io_req_init_async(req);
 		req->flags |= REQ_F_INFLIGHT;
 
-- 
2.24.0