[PATCH 2/2] io_uring: fix leaving invalid req->flags

[Pavel Begunkov <asml.silence@xxxxxxxxx>]

sqe->flags are subset of req flags, so incorrectly copied may span into
in-kernel flags and wreck havoc, e.g. by setting REQ_F_INFLIGHT.

Fixes: 5be9ad1e4287e ("io_uring: optimise io_init_req() flags setting")
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
 fs/io_uring.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index ce5fccf00367..2bd10f89b837 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6687,8 +6687,10 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	req->result = 0;
 
 	/* enforce forwards compatibility on users */
-	if (unlikely(sqe_flags & ~SQE_VALID_FLAGS))
+	if (unlikely(sqe_flags & ~SQE_VALID_FLAGS)) {
+		req->flags = 0;
 		return -EINVAL;
+	}
 
 	if (unlikely(req->opcode >= IORING_OP_LAST))
 		return -EINVAL;
-- 
2.24.0