Validate ClientHello extension field length

RT#4069

Reviewed-by: Emilia Käsper <emilia@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>

diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index aeae5b0cba6a9e64e4a97e673211e0041892f7ee..4975c108532a63a8d0eaea5aaac7862bee7c5262 100644 (file)
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -1927,6 +1927,9 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
     if (!PACKET_get_net_2(pkt, &len))
         goto err;
 
+    if (PACKET_remaining(pkt) != len)
+        goto err;
+
     while (PACKET_get_net_2(pkt, &type) && PACKET_get_net_2(pkt, &size)) {
         PACKET subpkt;