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)

diff --git a/ssl/ssl_sess.c b/ssl/ssl_sess.c
index 4c7f5d8b4e32d3e09690e8f313d62ddd08cbc95b..eb7936b4e1d390d86d0e23e854dfc987aee51cb6 100644 (file)
--- a/ssl/ssl_sess.c
+++ b/ssl/ssl_sess.c
@@ -478,7 +478,7 @@ 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) {