[FFmpeg-cvslog] mov: validate number of DataReferenceBox entries against box size

[Janne Grunau]

ffmpeg | branch: master | Janne Grunau <janne-libav at jannau.net> | Mon Nov 26 22:18:31 2012 +0100| [8cc2fa1e5db0655c053b35c948ef05ba0fe13707] | committer: Janne Grunau

mov: validate number of DataReferenceBox entries against box size

Avoids a 2G memory allocation and parsing of random data in
mov_read_dref(). The fuzzed sample sample.mp4_s224424 triggers this.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=8cc2fa1e5db0655c053b35c948ef05ba0fe13707
---

 libavformat/mov.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavformat/mov.c b/libavformat/mov.c
index a0ede86..8503a7e 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -351,6 +351,7 @@ static int mov_read_chpl(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     return 0;
 }
 
+#define MIN_DATA_ENTRY_BOX_SIZE 12
 static int mov_read_dref(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 {
     AVStream *st;
@@ -364,7 +365,8 @@ static int mov_read_dref(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 
     avio_rb32(pb); // version + flags
     entries = avio_rb32(pb);
-    if (entries >= UINT_MAX / sizeof(*sc->drefs))
+    if (entries >  (atom.size - 1) / MIN_DATA_ENTRY_BOX_SIZE + 1 ||
+        entries >= UINT_MAX / sizeof(*sc->drefs))
         return AVERROR_INVALIDDATA;
     av_free(sc->drefs);
     sc->drefs = av_mallocz(entries * sizeof(*sc->drefs));