[FFmpeg-cvslog] avcodec/mpeg4videodec: Check sprite delta upshift against overflowing.

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Wed Jun 14 23:55:17 2017 +0200| [7bca492cfcc7e17e7d9ea5697c318283bee45984] | committer: Michael Niedermayer

avcodec/mpeg4videodec: Check sprite delta upshift against overflowing.

Fixes: runtime error: signed integer overflow: -268386304 * 16 cannot be represented in type 'int'
Fixes: 2204/clusterfuzz-testcase-minimized-5616756909408256

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 12245ab1f677074b8ff83e87f76a41aba692ccd6)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7bca492cfcc7e17e7d9ea5697c318283bee45984
---

 libavcodec/mpeg4videodec.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
index aabcde59fc..a9aa6d67d0 100644
--- a/libavcodec/mpeg4videodec.c
+++ b/libavcodec/mpeg4videodec.c
@@ -360,14 +360,16 @@ static int mpeg4_decode_sprite_trajectory(Mpeg4DecContext *ctx, GetBitContext *g
         int shift_y = 16 - ctx->sprite_shift[0];
         int shift_c = 16 - ctx->sprite_shift[1];
 
-        if (shift_c < 0 || shift_y < 0 ||
-            FFABS(sprite_offset[0][0]) >= INT_MAX >> shift_y  ||
-            FFABS(sprite_offset[1][0]) >= INT_MAX >> shift_c  ||
-            FFABS(sprite_offset[0][1]) >= INT_MAX >> shift_y  ||
-            FFABS(sprite_offset[1][1]) >= INT_MAX >> shift_c
-        ) {
-            avpriv_request_sample(s->avctx, "Too large sprite shift or offset");
-            goto overflow;
+        for (i = 0; i < 2; i++) {
+            if (shift_c < 0 || shift_y < 0 ||
+                FFABS(  sprite_offset[0][i]) >= INT_MAX >> shift_y  ||
+                FFABS(  sprite_offset[1][i]) >= INT_MAX >> shift_c  ||
+                FFABS(s->sprite_delta[0][i]) >= INT_MAX >> shift_y  ||
+                FFABS(s->sprite_delta[1][i]) >= INT_MAX >> shift_y
+            ) {
+                avpriv_request_sample(s->avctx, "Too large sprite shift, delta or offset");
+                goto overflow;
+            }
         }
 
         for (i = 0; i < 2; i++) {