[FFmpeg-cvslog] avcodec/exr: Check remaining bits in last get code loop

[Michael Niedermayer]

ffmpeg | branch: release/3.3 | Michael Niedermayer <michael at niedermayer.cc> | Wed Feb 14 13:01:46 2018 +0100| [659a23e89fbaf649f8984a9d5dfd5479e5a37386] | committer: Michael Niedermayer

avcodec/exr: Check remaining bits in last get code loop

Fixes: runtime error: shift exponent -7 is negative
Fixes: 3902/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_EXR_fuzzer-6081926122176512

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 dd8351b1184b8054925c28ecc5fcb6dbbc177fad)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=659a23e89fbaf649f8984a9d5dfd5479e5a37386
---

 libavcodec/exr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/exr.c b/libavcodec/exr.c
index fe978805c5..b27132d6bb 100644
--- a/libavcodec/exr.c
+++ b/libavcodec/exr.c
@@ -574,7 +574,7 @@ static int huf_decode(const uint64_t *hcode, const HufDec *hdecod,
     while (lc > 0) {
         const HufDec pl = hdecod[(c << (HUF_DECBITS - lc)) & HUF_DECMASK];
 
-        if (pl.len) {
+        if (pl.len && lc >= pl.len) {
             lc -= pl.len;
             get_code(pl.lit, rlc, c, lc, gb, out, oe, outb);
         } else {