avcodec/mpeg4videodec: Check the other 3 sprite points for intermediate overflows
authorMichael Niedermayer <michael@niedermayer.cc>
Thu, 23 Feb 2017 21:33:16 +0000 (22:33 +0100)
committerMichael Niedermayer <michael@niedermayer.cc>
Thu, 23 Feb 2017 23:38:45 +0000 (00:38 +0100)
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@niedermayer.cc>
libavcodec/mpeg4videodec.c

index 2216cd5..dac9538 100644 (file)
@@ -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;
     }