io_uring/msg_ring: fix remote queue to disabled ring

commit 8579538c89e33ce78be2feb41e07489c8cbf8f31 upstream.

IORING_SETUP_R_DISABLED rings don't have the submitter task set, so
it's not always safe to use ->submitter_task. Disallow posting msg_ring
messaged to disabled rings. Also add task NULL check for loosy sync
around testing for IORING_SETUP_R_DISABLED.

Cc: stable@vger.kernel.org
Fixes: 6d043ee1164ca ("io_uring: do msg_ring in target task via tw")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c
index a49ccab..7d5b544 100644 (file)
--- a/io_uring/msg_ring.c
+++ b/io_uring/msg_ring.c
@@ -30,6 +30,8 @@ static int io_msg_ring_data(struct io_kiocb *req)
 
        if (msg->src_fd || msg->dst_fd || msg->flags)
                return -EINVAL;
+       if (target_ctx->flags & IORING_SETUP_R_DISABLED)
+               return -EBADFD;
 
        if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0, true))
                return 0;
@@ -84,6 +86,8 @@ static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
 
        if (target_ctx == ctx)
                return -EINVAL;
+       if (target_ctx->flags & IORING_SETUP_R_DISABLED)
+               return -EBADFD;
 
        ret = io_double_lock_ctx(ctx, target_ctx, issue_flags);
        if (unlikely(ret))