commit efb0e16ee5fbe64dd67ba4b84c3c24dc55fa44c6
author Adam Langley <agl@google.com> Thu Jul 09 11:35:04 2015 -0700
committer Adam Langley <agl@google.com> Thu Jul 09 22:47:14 2015 +0000
tree bdb3688cd8a7b6364ff9659b9d3c3773bd948744
parent d822ed811a1242c18ea7b16a905f0abdb2061f66

Reject empty ALPN protocols.

https://tools.ietf.org/html/rfc7301#section-3.1 specifies that a
ProtocolName may not be empty. This change enforces this in ClientHello
and ServerHello messages.

Thanks to Doug Hogan for reporting this.

Change-Id: Iab879c83145007799b94d2725201ede1a39e4596
Reviewed-on: https://boringssl-review.googlesource.com/5390
Reviewed-by: Adam Langley <agl@google.com>

ssl/t1_lib.c

diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 7005704..1a5594d 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -1674,7 +1674,9 @@
   while (CBS_len(&protocol_name_list_copy) > 0) {
     CBS protocol_name;
 
-    if (!CBS_get_u8_length_prefixed(&protocol_name_list_copy, &protocol_name)) {
+    if (!CBS_get_u8_length_prefixed(&protocol_name_list_copy, &protocol_name) ||
+        /* Empty protocol names are forbidden. */
+        CBS_len(&protocol_name) == 0) {
       goto parse_error;
     }
   }
@@ -2118,6 +2120,8 @@
       if (!CBS_get_u16_length_prefixed(&extension, &protocol_name_list) ||
           CBS_len(&extension) != 0 ||
           !CBS_get_u8_length_prefixed(&protocol_name_list, &protocol_name) ||
+          /* Empty protocol names are forbidden. */
+          CBS_len(&protocol_name) == 0 ||
           CBS_len(&protocol_name_list) != 0) {
         *out_alert = SSL_AD_DECODE_ERROR;
         return 0;