[FFmpeg-cvslog] avcodec/jpeg2000dec: Check that there are enough bytes for all tiles

[Michael Niedermayer]

ffmpeg | branch: release/3.4 | Michael Niedermayer <michael at niedermayer.cc> | Mon Jul  2 18:40:08 2018 +0200| [428c3e5975d3cf742b97aeb4a8352ed3bcd8bb0d] | committer: Michael Niedermayer

avcodec/jpeg2000dec: Check that there are enough bytes for all tiles

Fixes: OOM
Fixes: 8781/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_fuzzer-5810709081358336

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 0898a3d9909960324e27d3a7a4f48c4effbb654a)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=428c3e5975d3cf742b97aeb4a8352ed3bcd8bb0d
---

 libavcodec/jpeg2000dec.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index d8325320de..0c3ebfcf11 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -342,7 +342,10 @@ static int get_siz(Jpeg2000DecoderContext *s)
     s->numXtiles = ff_jpeg2000_ceildiv(s->width  - s->tile_offset_x, s->tile_width);
     s->numYtiles = ff_jpeg2000_ceildiv(s->height - s->tile_offset_y, s->tile_height);
 
-    if (s->numXtiles * (uint64_t)s->numYtiles > INT_MAX/sizeof(*s->tile)) {
+    // There must be at least a SOT and SOD per tile, their minimum size is 14
+    if (s->numXtiles * (uint64_t)s->numYtiles > INT_MAX/sizeof(*s->tile) ||
+        s->numXtiles * s->numYtiles * 14LL > bytestream2_size(&s->g)
+    ) {
         s->numXtiles = s->numYtiles = 0;
         return AVERROR(EINVAL);
     }