When token lookup on MP_JOIN 3rd ack fails, the server
socket closes with a reset the incoming child. Such socket
has the 'is_mptcp' flag set, but no msk socket associated
- due to the failed lookup.
While crafting the reset packet mptcp_established_options_mp()
will try to dereference the child's master socket, causing
a NULL ptr dereference.
This change addresses the issue with explicit fallback to
TCP in such error path.
Fixes:
729cd6436f35 ("mptcp: cope better with MP_JOIN failure")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp_sk(sk)->is_mptcp = 0;
}
+static void subflow_drop_ctx(struct sock *ssk)
+{
+ struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
+
+ if (!ctx)
+ return;
+
+ subflow_ulp_fallback(ssk, ctx);
+ if (ctx->conn)
+ sock_put(ctx->conn);
+
+ kfree_rcu(ctx, rcu);
+}
+
static struct sock *subflow_syn_recv_sock(const struct sock *sk,
struct sk_buff *skb,
struct request_sock *req,
if (fallback_is_fatal)
goto dispose_child;
- if (ctx) {
- subflow_ulp_fallback(child, ctx);
- kfree_rcu(ctx, rcu);
- }
+ subflow_drop_ctx(child);
goto out;
}
return child;
dispose_child:
+ subflow_drop_ctx(child);
tcp_rsk(req)->drop_req = true;
tcp_send_active_reset(child, GFP_ATOMIC);
inet_csk_prepare_for_destroy_sock(child);