[FFmpeg-cvslog] avcodec/diracdec: Check perspective_exp and zrs_exp.

[Michael Niedermayer]

ffmpeg | branch: release/3.1 | Michael Niedermayer <michael at niedermayer.cc> | Tue Aug 15 03:32:43 2017 +0200| [df2efc212dabc2cccb7101e15bba0c78cb5d80b3] | committer: Michael Niedermayer

avcodec/diracdec: Check perspective_exp and zrs_exp.

Fixes: undefined shift
Fixes: runtime error: shift exponent 264 is too large for 32-bit type 'int'
Fixes: 2860/clusterfuzz-testcase-minimized-4672811689836544

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 1e6cab874512070b36267a5a53fd053f90072fa2)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=df2efc212dabc2cccb7101e15bba0c78cb5d80b3
---

 libavcodec/diracdec.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libavcodec/diracdec.c b/libavcodec/diracdec.c
index 579ff97322..6f6a0ece45 100644
--- a/libavcodec/diracdec.c
+++ b/libavcodec/diracdec.c
@@ -1082,6 +1082,10 @@ static int dirac_unpack_prediction_parameters(DiracContext *s)
                 s->globalmc[ref].perspective[0]  = dirac_get_se_golomb(gb);
                 s->globalmc[ref].perspective[1]  = dirac_get_se_golomb(gb);
             }
+            if (s->globalmc[ref].perspective_exp + (uint64_t)s->globalmc[ref].zrs_exp > 30) {
+                return AVERROR_INVALIDDATA;
+            }
+
         }
     }