[FFmpeg-cvslog] avcodec/mpeg4videodec: Check the other 3 sprite points for intermediate overflows

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Feb 23 22:33:16 2017 +0100| [76ba09d18245a2a41dc5f93a60fd00cdf358cb1f] | committer: Michael Niedermayer

avcodec/mpeg4videodec: Check the other 3 sprite points for intermediate overflows

This is not necessarily specific to fuzzed files

Fixes: Multiple integer overflows
Fixes: 656/clusterfuzz-testcase-6463814516080640
Fixes: 658/clusterfuzz-testcase-6691260146384896

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=76ba09d18245a2a41dc5f93a60fd00cdf358cb1f
---

 libavcodec/mpeg4videodec.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
index 2216cd5..dac9538 100644
--- a/libavcodec/mpeg4videodec.c
+++ b/libavcodec/mpeg4videodec.c
@@ -384,6 +384,13 @@ static int mpeg4_decode_sprite_trajectory(Mpeg4DecContext *ctx, GetBitContext *g
             s->sprite_delta[0][i]  *= 1 << shift_y;
             s->sprite_delta[1][i]  *= 1 << shift_y;
             ctx->sprite_shift[i]     = 16;
+
+            if (llabs(s->sprite_offset[i][0] + s->sprite_delta[i][0] * (int64_t)w) >= INT_MAX ||
+                llabs(s->sprite_offset[i][0] + s->sprite_delta[i][1] * (int64_t)h) >= INT_MAX ||
+                llabs(s->sprite_offset[i][0] + s->sprite_delta[i][0] * (int64_t)w + s->sprite_delta[i][1] * (int64_t)h) >= INT_MAX) {
+                avpriv_request_sample(s->avctx, "Overflow on sprite points");
+                return AVERROR_PATCHWELCOME;
+            }
         }
         s->real_sprite_warping_points = ctx->num_sprite_warping_points;
     }