[vlc-commits] avi: Fix integer overflow

[Hugo Beauzée-Luyssen]

vlc | branch: master | Hugo Beauzée-Luyssen <hugo at beauzee.fr> | Mon Nov  9 09:54:27 2020 +0100| [a4b1de184faf86617b4432954c1984e0027fb246] | committer: Hugo Beauzée-Luyssen

avi: Fix integer overflow

Which would in turn cause a size verification failure, leading to a
buffer overflow
Reported by: Zhen Zhou, NSFOCUS Security Team

> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=a4b1de184faf86617b4432954c1984e0027fb246
---

 modules/demux/avi/avi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/modules/demux/avi/avi.c b/modules/demux/avi/avi.c
index 9174b3167b..c3aa70ef57 100644
--- a/modules/demux/avi/avi.c
+++ b/modules/demux/avi/avi.c
@@ -2933,7 +2933,7 @@ static void AVI_ExtractSubtitle( demux_t *p_demux,
     if( i_size < 6 || GetWLE( &p[0] ) != 0x04 )
         goto exit;
     const unsigned i_payload = GetDWLE( &p[2] );
-    if( i_size < 6 + i_payload || i_payload <= 0 )
+    if( i_size - 6 < i_payload || i_payload == 0 )
         goto exit;
     p += 6;
     i_size -= 6;