[FFmpeg-cvslog] avcodec/jpeg2000dec: check len before parsing header

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Fri Jun 14 19:20:10 2013 +0200| [69e4d8e6a4cefdf1b19f5d4d1293aa881d6064e8] | committer: Michael Niedermayer

avcodec/jpeg2000dec: check len before parsing header

Fixes out of array read

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=69e4d8e6a4cefdf1b19f5d4d1293aa881d6064e8
---

 libavcodec/jpeg2000dec.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index 11fa7f6..f821292 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -1249,9 +1249,9 @@ static int jpeg2000_read_main_headers(Jpeg2000DecoderContext *s)
         if (marker == JPEG2000_EOC)
             break;
 
-        if (bytestream2_get_bytes_left(&s->g) < 2)
+        len = bytestream2_get_be16(&s->g);
+        if (len < 2 || bytestream2_get_bytes_left(&s->g) < len - 2)
             return AVERROR(EINVAL);
-        len = bytestream2_get_be16u(&s->g);
         switch (marker) {
         case JPEG2000_SIZ:
             ret = get_siz(s);