[FFmpeg-devel] [PATCH 1/4] avcodec/mpeg4videodec: Fix runtime error: left shift of negative value -2650

Michael Niedermayer michael at niedermayer.cc
Sun Feb 26 21:27:59 EET 2017


Fixes: 674/clusterfuzz-testcase-6713275880308736

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/mpeg4videodec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
index dac9538436..9f9374d550 100644
--- a/libavcodec/mpeg4videodec.c
+++ b/libavcodec/mpeg4videodec.c
@@ -283,12 +283,12 @@ static int mpeg4_decode_sprite_trajectory(Mpeg4DecContext *ctx, GetBitContext *g
         ctx->sprite_shift[1]   = 0;
         break;
     case 2:
-        s->sprite_offset[0][0] = (sprite_ref[0][0] << (alpha + rho)) +
+        s->sprite_offset[0][0] = (sprite_ref[0][0] * (1 << alpha + rho)) +
                                  (-r * sprite_ref[0][0] + virtual_ref[0][0]) *
                                  (-vop_ref[0][0]) +
                                  (r * sprite_ref[0][1] - virtual_ref[0][1]) *
                                  (-vop_ref[0][1]) + (1 << (alpha + rho - 1));
-        s->sprite_offset[0][1] = (sprite_ref[0][1] << (alpha + rho)) +
+        s->sprite_offset[0][1] = (sprite_ref[0][1] * (1 << alpha + rho)) +
                                  (-r * sprite_ref[0][1] + virtual_ref[0][1]) *
                                  (-vop_ref[0][0]) +
                                  (-r * sprite_ref[0][0] + virtual_ref[0][0]) *
-- 
2.11.0



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