Merge pull request #10366 from crest42/gnrc_udp_use_after_free

gnrc_sock_[udp|ip]: read return value for _recv after release

sys/net/gnrc/sock/ip/gnrc_sock_ip.c

@@ -120,8 +120,9 @@ ssize_t sock_ip_recv(sock_ip_t *sock, void *data, size_t max_len,
         return -EPROTO;
     }
     memcpy(data, pkt->data, pkt->size);
+    res = (int)pkt->size;
     gnrc_pktbuf_release(pkt);
-    return (int)pkt->size;
+    return res;
 }
 
 ssize_t sock_ip_send(sock_ip_t *sock, const void *data, size_t len,

sys/net/gnrc/sock/udp/gnrc_sock_udp.c

@@ -215,8 +215,9 @@ ssize_t sock_udp_recv(sock_udp_t *sock, void *data, size_t max_len,
         return -EPROTO;
     }
     memcpy(data, pkt->data, pkt->size);
+    res = (int)pkt->size;
     gnrc_pktbuf_release(pkt);
-    return (int)pkt->size;
+    return res;
 }
 
 ssize_t sock_udp_send(sock_udp_t *sock, const void *data, size_t len,