[FFmpeg-cvslog] avcodec/vmixdec: Fix several integer anomalies

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sun Jun 18 22:41:01 2023 +0200| [574f3aaeff6d04762f02044f1ee1e3564bc3ad00] | committer: Michael Niedermayer

avcodec/vmixdec: Fix several integer anomalies

Fixes: vmixdec.c:132:34: runtime error: signed integer overflow: -2147483648 * 1856 cannot be represented in type 'int'
Fixes: vmixdec.c:119:20: runtime error: signed integer overflow: -1256 + -2147483648 cannot be represented in type 'int'
Fixes: vmixdec.c:137:36: runtime error: signed integer overflow: 2147483416 * 16 cannot be represented in type 'int'
Fixes: 59843/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VMIX_fuzzer-4857434624360448

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=574f3aaeff6d04762f02044f1ee1e3564bc3ad00
---

 libavcodec/vmixdec.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libavcodec/vmixdec.c b/libavcodec/vmixdec.c
index d0f2219a67..b77c90929a 100644
--- a/libavcodec/vmixdec.c
+++ b/libavcodec/vmixdec.c
@@ -116,7 +116,7 @@ static int decode_dcac(AVCodecContext *avctx,
                 dc_run--;
             } else {
                 dc_v = get_se_golomb_vmix(dc_gb);
-                dc += dc_v;
+                dc += (unsigned)dc_v;
                 if (!dc_v)
                     dc_run = get_ue_golomb_long(dc_gb);
             }
@@ -129,12 +129,12 @@ static int decode_dcac(AVCodecContext *avctx,
 
                 ac_v = get_se_golomb_vmix(ac_gb);
                 i = scan[n];
-                block[i] = (ac_v * factors[i]) >> 4;
+                block[i] = ((unsigned)ac_v * factors[i]) >> 4;
                 if (!ac_v)
                     ac_run = get_ue_golomb_long(ac_gb);
             }
 
-            block[0] = ((dc + add) * 16) >> 4;
+            block[0] = dc + add;
             s->idsp.idct_put(dst + x, linesize, block);
         }