[FFmpeg-cvslog] avcodec/tiff: Do not overrun the array ends in dng_blit()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Wed Jul  1 23:05:22 2020 +0200| [f35caea77f76c62bd0e392e514a84833ab1e0c83] | committer: Michael Niedermayer

avcodec/tiff: Do not overrun the array ends in dng_blit()

Fixes: out of array access
Fixes: 23589/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_TIFF_fuzzer-5110559589793792.fuzz

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=f35caea77f76c62bd0e392e514a84833ab1e0c83
---

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

diff --git a/libavcodec/tiff.c b/libavcodec/tiff.c
index dc24d055ec..d93a02b07e 100644
--- a/libavcodec/tiff.c
+++ b/libavcodec/tiff.c
@@ -859,8 +859,11 @@ static void dng_blit(TiffContext *s, uint8_t *dst, int dst_stride,
             }
         } else {
             for (line = 0; line < height; line++) {
+                uint8_t *dst_u8 = dst;
+                const uint8_t *src_u8 = src;
+
                 for (col = 0; col < width; col++)
-                    *dst++ = dng_process_color8(*src++, s->dng_lut, s->black_level, scale_factor);
+                    *dst_u8++ = dng_process_color8(*src_u8++, s->dng_lut, s->black_level, scale_factor);
 
                 dst += dst_stride;
                 src += src_stride;