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()")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
net/mptcp/fastopen.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
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;
--
2.39.2