From: Paolo Abeni Date: Tue, 11 Apr 2023 20:42:11 +0000 (+0200) Subject: mptcp: fix NULL pointer dereference on fastopen early fallback X-Git-Tag: v6.3-rc7~20^2~6^2~1 X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=c0ff6f6da66a7791a32c0234388b1bdc00244917;p=tomoyo%2Ftomoyo-test1.git mptcp: fix NULL pointer dereference on fastopen early fallback In case of early fallback to TCP, subflow_syn_recv_sock() deletes the subflow context before returning the newly allocated sock to the caller. The fastopen path does not cope with the above unconditionally dereferencing the subflow context. Fixes: 36b122baf6a8 ("mptcp: add subflow_v(4,6)_send_synack()") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts Signed-off-by: Matthieu Baerts Signed-off-by: Jakub Kicinski --- diff --git a/net/mptcp/fastopen.c b/net/mptcp/fastopen.c index d237d142171c..bceaab8dd8e4 100644 --- a/net/mptcp/fastopen.c +++ b/net/mptcp/fastopen.c @@ -9,11 +9,18 @@ void mptcp_fastopen_subflow_synack_set_params(struct mptcp_subflow_context *subflow, struct request_sock *req) { - struct sock *ssk = subflow->tcp_sock; - struct sock *sk = subflow->conn; + struct sock *sk, *ssk; struct sk_buff *skb; struct tcp_sock *tp; + /* on early fallback the subflow context is deleted by + * subflow_syn_recv_sock() + */ + if (!subflow) + return; + + ssk = subflow->tcp_sock; + sk = subflow->conn; tp = tcp_sk(ssk); subflow->is_mptfo = 1;