[FFmpeg-cvslog] avcodec/brenderpix: Check input size before allocating image

[Michael Niedermayer]

ffmpeg | branch: release/4.2 | Michael Niedermayer <michael at niedermayer.cc> | Fri Jul 26 14:16:16 2019 +0200| [598496e50cfd6f6484fc1caf8ab503c47e76a767] | committer: Michael Niedermayer

avcodec/brenderpix: Check input size before allocating image

An incomplete image is not supported prior to this and will
not produce any output. This commit moves the failure before
time consuming operations.

Fixes: Timeout (81sec -> 76ms)
Fixes: 15723/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_BRENDER_PIX_fuzzer-5147265653538816

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 38b6c48c4300343f4703019a90a332773e64e11b)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=598496e50cfd6f6484fc1caf8ab503c47e76a767
---

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

diff --git a/libavcodec/brenderpix.c b/libavcodec/brenderpix.c
index 0556858de1..46b7a59aa4 100644
--- a/libavcodec/brenderpix.c
+++ b/libavcodec/brenderpix.c
@@ -204,6 +204,10 @@ static int pix_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
         avpriv_request_sample(avctx, "Format %d", hdr.format);
         return AVERROR_PATCHWELCOME;
     }
+    bytes_per_scanline = bytes_pp * hdr.width;
+
+    if (bytestream2_get_bytes_left(&gb) < hdr.height * bytes_per_scanline)
+        return AVERROR_INVALIDDATA;
 
     if ((ret = ff_set_dimensions(avctx, hdr.width, hdr.height)) < 0)
         return ret;
@@ -261,7 +265,6 @@ static int pix_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
     bytestream2_skip(&gb, 8);
 
     // read the image data to the buffer
-    bytes_per_scanline = bytes_pp * hdr.width;
     bytes_left = bytestream2_get_bytes_left(&gb);
 
     if (chunk_type != IMAGE_DATA_CHUNK || data_len != bytes_left ||