From 45ecb42abc0200b6a0d67bd4278f22d8c9e6fea8 Mon Sep 17 00:00:00 2001
From: David Hotham <david.hotham@metaswitch.com>
Date: Fri, 1 Jan 2021 13:10:07 +0000
Subject: [PATCH] fix: avoid accessing unowned memory (#17)

---
 src/scanner.cc | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/scanner.cc b/src/scanner.cc
index 5116fe8..16e0af0 100644
--- a/src/scanner.cc
+++ b/src/scanner.cc
@@ -655,9 +655,10 @@ struct Scanner {
 
     bool allow_comment = !(VLD[R_DQT_STR_CTN] || VLD[BR_DQT_STR_CTN] || VLD[R_SQT_STR_CTN] || VLD[BR_SQT_STR_CTN]);
 
-    int16_t *ind_ptr = &ind_len_stk.back();
-    int16_t cur_ind = *ind_ptr--;
-    int16_t prt_ind = *ind_ptr;
+    vector<int16_t>::reverse_iterator ind_ptr = ind_len_stk.rbegin();
+    vector<int16_t>::reverse_iterator ind_end = ind_len_stk.rend();
+    int16_t cur_ind = *ind_ptr++;
+    int16_t prt_ind = ind_ptr == ind_end ? -1 : *ind_ptr;
     int16_t cur_ind_typ = ind_typ_stk.back();
 
     bool has_tab_ind = false;