[FFmpeg-cvslog] avcodec/diracdec: Count truncated parts as errors in decode_component()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Fri Mar  8 15:43:08 2019 +0100| [dd2a2a51fe47361fa82c67f2a417e1706713eaef] | committer: Michael Niedermayer

avcodec/diracdec: Count truncated parts as errors in decode_component()

Fixes: Timeout (29sec -> 4sec)
Fixes: 13150/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DIRAC_fuzzer-5690185671507968

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=dd2a2a51fe47361fa82c67f2a417e1706713eaef
---

 libavcodec/diracdec.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libavcodec/diracdec.c b/libavcodec/diracdec.c
index 30b4bfad79..a1e759f656 100644
--- a/libavcodec/diracdec.c
+++ b/libavcodec/diracdec.c
@@ -685,7 +685,10 @@ static int decode_component(DiracContext *s, int comp)
                 }
                 align_get_bits(&s->gb);
                 b->coeff_data = s->gb.buffer + get_bits_count(&s->gb)/8;
-                b->length = FFMIN(b->length, FFMAX(get_bits_left(&s->gb)/8, 0));
+                if (b->length > FFMAX(get_bits_left(&s->gb)/8, 0)) {
+                    b->length = FFMAX(get_bits_left(&s->gb)/8, 0);
+                    damaged_count ++;
+                }
                 skip_bits_long(&s->gb, b->length*8);
             }
         }