[vlc-commits] demux: mp4: fix buffer overflow in parsing of string boxes.

[Fabian Yamaguchi]

vlc | branch: master | Fabian Yamaguchi <fyamagu at gwdg.de> | Fri Dec  5 13:52:42 2014 +0100| [456b22643e7fbbafe7ed8189d2f084ab6193b2c5] | committer: Jean-Baptiste Kempf

demux: mp4: fix buffer overflow in parsing of string boxes.

We ensure that pbox->i_size is never smaller than 8 to avoid an
integer underflow in the third argument of the subsequent call to
memcpy. We also make sure no truncation occurs when passing values
derived from the 64 bit integer p_box->i_size to arguments of malloc
and memcpy that may be 32 bit integers on 32 bit platforms.

Signed-off-by: Jean-Baptiste Kempf <jb at videolan.org>

> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=456b22643e7fbbafe7ed8189d2f084ab6193b2c5
---

 modules/demux/mp4/libmp4.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/modules/demux/mp4/libmp4.c b/modules/demux/mp4/libmp4.c
index 9429ff3..a1be0c2 100644
--- a/modules/demux/mp4/libmp4.c
+++ b/modules/demux/mp4/libmp4.c
@@ -2858,6 +2858,9 @@ static int MP4_ReadBox_String( stream_t *p_stream, MP4_Box_t *p_box )
 {
     MP4_READBOX_ENTER( MP4_Box_data_string_t );
 
+    if( p_box->i_size < 8 || p_box->i_size - 7 > SIZE_MAX)
+        MP4_READBOX_EXIT( 0 );
+
     p_box->data.p_string->psz_text = malloc( p_box->i_size + 1 - 8 ); /* +\0, -name, -size */
     if( p_box->data.p_string->psz_text == NULL )
         MP4_READBOX_EXIT( 0 );