commit 328a7b550ee1cfcd81495f81b3b37e85f7ee2e55
author Kazuho Oku <kazuhooku@gmail.com> Sat Feb 25 09:59:34 2023 +0900
committer Kazuho Oku <kazuhooku@gmail.com> Sat Feb 25 09:59:34 2023 +0900
tree af43dd528b4f415b94981f497436ffcfabccbb00
parent 3b3a910c5cad139e3ac3ebca1a4b93604263e6c8

TLS/1.0 and 1.1 CH may lack extensions block

lib/picotls.c

diff --git a/lib/picotls.c b/lib/picotls.c
index dc71e66..dcde89c 100644
--- a/lib/picotls.c
+++ b/lib/picotls.c
@@ -3561,9 +3561,14 @@
         src = end;
     });
 
-    ch->first_extension_at = src - start + 2;
+    /* CH defined in TLS versions below 1.2 do not have extensions; so bail out after parsing the main variables */
+    if (ch->legacy_version < 0x0303) {
+        ret = PTLS_ALERT_PROTOCOL_VERSION;
+        goto Exit;
+    }
 
     /* decode extensions */
+    ch->first_extension_at = src - start + 2;
     decode_extensions(src, end, PTLS_HANDSHAKE_TYPE_CLIENT_HELLO, &exttype, {
         ch->psk.is_last_extension = 0;
         if (ctx->on_extension != NULL && tls_cbarg != NULL &&