[FFmpeg-devel,2/3] avcodec/vc1_pred: Fix invalid shifts in scaleforopp()

Submitted by Michael Niedermayer on Sept. 11, 2019, 12:18 a.m.

Details

Message ID 20190911001843.2680-2-michael@niedermayer.cc
State New
Headers show

Commit Message

Michael Niedermayer Sept. 11, 2019, 12:18 a.m.
Fixes: left shift of negative value -2
Fixes: 16964/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VC1IMAGE_fuzzer-5757853565976576

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/vc1_pred.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

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diff --git a/libavcodec/vc1_pred.c b/libavcodec/vc1_pred.c
index e1ad0e1d7d..f70956e739 100644
--- a/libavcodec/vc1_pred.c
+++ b/libavcodec/vc1_pred.c
@@ -191,9 +191,9 @@  static av_always_inline int scaleforopp(VC1Context *v, int n /* MV */,
     n >>= hpel;
     if (v->s.pict_type == AV_PICTURE_TYPE_B && !v->second_field && dir == 1) {
         if (dim)
-            n = scaleforopp_y(v, n, dir) << hpel;
+            n = scaleforopp_y(v, n, dir) * (1 << hpel);
         else
-            n = scaleforopp_x(v, n) << hpel;
+            n = scaleforopp_x(v, n)      * (1 << hpel);
         return n;
     }
     if (v->s.pict_type != AV_PICTURE_TYPE_B)