From 9e91d21625867f73825c3fc61588749118ad1a6f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6ren=20Tempel?= <soeren+git@soeren-tempel.net>
Date: Mon, 12 Aug 2019 21:49:19 +0200
Subject: [PATCH] net/gnrc/tcp: fix uninitialized memory access

From the gnrc_pktbuf_mark documentation:

	    It's not guaranteed that `result->data` points to the
	    same address as the original `pkt->data.

Thus it should be necessary to update the `hdr` pointer.
---
 sys/net/gnrc/transport_layer/tcp/gnrc_tcp_eventloop.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sys/net/gnrc/transport_layer/tcp/gnrc_tcp_eventloop.c b/sys/net/gnrc/transport_layer/tcp/gnrc_tcp_eventloop.c
index db7fb5621c26..02ae9f9c0ded 100644
--- a/sys/net/gnrc/transport_layer/tcp/gnrc_tcp_eventloop.c
+++ b/sys/net/gnrc/transport_layer/tcp/gnrc_tcp_eventloop.c
@@ -162,6 +162,7 @@ static int _receive(gnrc_pktsnip_t *pkt)
             return -ENOMSG;
         }
         pkt->type = GNRC_NETTYPE_UNDEF;
+        hdr = (tcp_hdr_t *)tcp->data;
     }
 
     /* Validate checksum */