[FFmpeg-cvslog] avcodec/pixlet: Fix reading invalid numbers of bits

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu May 18 16:51:08 2017 +0200| [d32ebce8fd79bb859ba4a04c92470a052f2aafa6] | committer: Michael Niedermayer

avcodec/pixlet: Fix reading invalid numbers of bits

Fixes: asertion failure
Fixes: 1664/clusterfuzz-testcase-minimized-6587801187385344

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d32ebce8fd79bb859ba4a04c92470a052f2aafa6
---

 libavcodec/pixlet.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/pixlet.c b/libavcodec/pixlet.c
index 05262648ae..0dfd5edbf7 100644
--- a/libavcodec/pixlet.c
+++ b/libavcodec/pixlet.c
@@ -229,6 +229,8 @@ static int read_high_coeffs(AVCodecContext *avctx, uint8_t *src, int16_t *dst, i
             cnt1 = get_bits(b, nbits);
         } else {
             pfx = 14 + ((((uint64_t)(value - 14)) >> 32) & (value - 14));
+            if (pfx < 1 || pfx > 25)
+                return AVERROR_INVALIDDATA;
             cnt1 *= (1 << pfx) - 1;
             shbits = show_bits(b, pfx);
             if (shbits <= 1) {