[FFmpeg-devel] [PATCH 2/5] avformat/matroskaenc: fix invalid pointer access if avio_get_dyn_buf failed

[lance.lmwang at gmail.com]

From: Limin Wang <lance.lmwang at gmail.com>

Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
---
 libavformat/matroskaenc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 784973a951..f0474da44f 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -374,9 +374,12 @@ static void end_ebml_master_crc32(AVIOContext *pb, AVIOContext **dyn_cp,
     put_ebml_length(pb, size, length_size);
     if (mkv->write_crc) {
         skip = 6; /* Skip reserved 6-byte long void element from the dynamic buffer. */
+        if (size > skip) {
         AV_WL32(crc, av_crc(av_crc_get_table(AV_CRC_32_IEEE_LE), UINT32_MAX, buf + skip, size - skip) ^ UINT32_MAX);
         put_ebml_binary(pb, EBML_ID_CRC32, crc, sizeof(crc));
+        }
     }
+    if (size > skip)
     avio_write(pb, buf + skip, size - skip);
 
     if (keep_buffer) {
-- 
2.21.0