Parse HelloVerifyRequest: avoid buffer overread on the cookie
In ssl_parse_hello_verify_request, we print cookie_len bytes without
checking that there are that many bytes left in ssl->in_msg. This
could potentially log data outside the received message (not a big
deal) and could potentially read from memory outside of the receive
buffer (which would be a remotely exploitable crash).
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 57e5d8a..9e0accc 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -1605,8 +1605,6 @@
}
cookie_len = *p++;
- MBEDTLS_SSL_DEBUG_BUF( 3, "cookie", p, cookie_len );
-
if( ( ssl->in_msg + ssl->in_msglen ) - p < cookie_len )
{
MBEDTLS_SSL_DEBUG_MSG( 1,
@@ -1615,6 +1613,7 @@
MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
}
+ MBEDTLS_SSL_DEBUG_BUF( 3, "cookie", p, cookie_len );
mbedtls_free( ssl->handshake->verify_cookie );