[FFmpeg-cvslog] avcodec/lagarith: Check dst/src in zero run code

[Michael Niedermayer]

ffmpeg | branch: release/4.1 | Michael Niedermayer <michael at niedermayer.cc> | Tue Jul 12 20:43:20 2022 +0200| [85d59a6a987b47717651e488dcf8a0de861c3b1e] | committer: Michael Niedermayer

avcodec/lagarith: Check dst/src in zero run code

Fixes: out of array access
Fixes: 48799/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LAGARITH_fuzzer-4764457825337344

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 9450f759748d02d1d284d2e4afd741cb0fe0c04a)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=85d59a6a987b47717651e488dcf8a0de861c3b1e
---

 libavcodec/lagarith.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavcodec/lagarith.c b/libavcodec/lagarith.c
index 1342c98961..54153c6a69 100644
--- a/libavcodec/lagarith.c
+++ b/libavcodec/lagarith.c
@@ -408,6 +408,9 @@ output_zeros:
         if (zero_run) {
             zero_run = 0;
             i += esc_count;
+            if (i >  end - dst ||
+                i >= src_end - src)
+                return AVERROR_INVALIDDATA;
             memcpy(dst, src, i);
             dst += i;
             l->zeros_rem = lag_calc_zero_run(src[i]);