nvme-tcp: fix UAF when detecting digest errors

We should also bail from the io_work loop when we set rd_enabled to true,
so we don't attempt to read data from the socket when the TCP stream is
already out-of-sync or corrupted.

Fixes: 3f2304f8 ("nvme-tcp: add NVMe over TCP host driver")
Reported-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/tcp.c

@@ -1229,7 +1229,7 @@ static void nvme_tcp_io_work(struct work_struct *w)
 		else if (unlikely(result < 0))
 			return;
 
-		if (!pending)
+		if (!pending || !queue->rd_enabled)
 			return;
 
 	} while (!time_after(jiffies, deadline)); /* quota is exhausted */