Piotr Caban : msvcrt: Don't write past buffer in strftime.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 30913ff564191d86d2d1d7ee5de359054fd30fff
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=30913ff564191d86d2d1d7ee5...

Author: Piotr Caban <piotr(a)codeweavers.com>
Date:   Mon Sep 30 16:52:07 2019 +0200

msvcrt: Don't write past buffer in strftime.

Signed-off-by: Piotr Caban <piotr(a)codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard(a)winehq.org>

---

 dlls/msvcrt/time.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/dlls/msvcrt/time.c b/dlls/msvcrt/time.c
index b7d11e0543..4aaa89ac0e 100644
--- a/dlls/msvcrt/time.c
+++ b/dlls/msvcrt/time.c
@@ -1197,10 +1197,12 @@ static MSVCRT_size_t strftime_helper(char *str, MSVCRT_size_t max, const char *f
         case 'T':
             if(!strftime_int(str, &ret, max, mstm->tm_hour, alternate ? 0 : 2, 0, 23))
                 return 0;
-            str[ret++] = ':';
+            if(ret < max)
+                str[ret++] = ':';
             if(!strftime_int(str, &ret, max, mstm->tm_min, alternate ? 0 : 2, 0, 59))
                 return 0;
-            str[ret++] = ':';
+            if(ret < max)
+                str[ret++] = ':';
             if(!strftime_int(str, &ret, max, mstm->tm_sec, alternate ? 0 : 2, 0, 59))
                 return 0;
             break;