[Minor] Check string length to avoid OOB reading

diff --git a/src/libutil/ssl_util.c b/src/libutil/ssl_util.c
index f2898d5927526016c046372c8c246ae2c7c7ebfa..c43ace45453cb7749cb2d48f0451da1945a646a6 100644 (file)
--- a/src/libutil/ssl_util.c
+++ b/src/libutil/ssl_util.c
@@ -401,7 +401,7 @@ rspamd_tls_set_error (gint retcode, const gchar *stage, GError **err)
 
                err_code = last_err;
 
-               if (reason->str[reason->len - 1] == ',') {
+               if (reason->len > 0 && reason->str[reason->len - 1] == ',') {
                        reason->str[reason->len - 1] = '\0';
                        reason->len --;
                }