[libav-stable] mjpegdec: validate parameters in mjpeg_decode_scan_progressive_ac

[Luca Barbato]

Module: libav
Branch: master
Commit: cfbd98abe82cfcb9984a18d08697251b72b110c8

Author:    Luca Barbato <lu_zero at gentoo.org>
Committer: Luca Barbato <lu_zero at gentoo.org>
Date:      Wed May 15 18:41:41 2013 +0200

mjpegdec: validate parameters in mjpeg_decode_scan_progressive_ac

Prevent out of buffer write when decoding broken samples.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable at libav.org

---

 libavcodec/mjpegdec.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 896fa99..934d1a2 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -941,6 +941,11 @@ static int mjpeg_decode_scan_progressive_ac(MJpegDecodeContext *s, int ss,
     int16_t *quant_matrix = s->quant_matrixes[s->quant_index[c]];
     GetBitContext mb_bitmask_gb;
 
+    if (ss < 0  || ss >= 64 ||
+        se < ss || se >= 64 ||
+        Ah < 0  || Al < 0)
+        return AVERROR_INVALIDDATA;
+
     if (mb_bitmask)
         init_get_bits(&mb_bitmask_gb, mb_bitmask, s->mb_width * s->mb_height);