From 9c5efc9c65be2d29fd01c02bba081b72ba025453 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Tue, 28 Apr 2015 15:28:23 +0100
Subject: [PATCH] Add sanity check to ssl_get_prev_session

Sanity check the |len| parameter to ensure it is positive. Thanks to Kevin
Wojtysiak (Int3 Solutions) and Paramjot Oberoi (Int3 Solutions) for
reporting this issue.

Reviewed-by: Andy Polyakov <appro@openssl.org>
(cherry picked from commit cb0f400b0cea2d2943f99b1e89c04ff6ed748cd5)
---
 ssl/ssl_sess.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ssl/ssl_sess.c b/ssl/ssl_sess.c
index dce90887bb..8b9945b475 100644
--- a/ssl/ssl_sess.c
+++ b/ssl/ssl_sess.c
@@ -449,7 +449,7 @@ int ssl_get_prev_session(SSL *s, unsigned char *session_id, int len,
     int r;
 #endif
 
-    if (len > SSL_MAX_SSL_SESSION_ID_LENGTH)
+    if (len < 0 || len > SSL_MAX_SSL_SESSION_ID_LENGTH)
         goto err;
 
     if (session_id + len > limit) {