[FFmpeg-devel] [PATCH 04/37] avformat/matroskadec: Don't zero unnecessarily

[Andreas Rheinhardt]

It is only necessary to zero the initial allocated memory used to store
the size of laced frames if the block used Xiph lacing. Otherwise no
unintialized data was ever used, so use av_malloc instead of av_mallocz.

Also use the correct type for the allocations.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
---
I checked this via the --enable-memory-poisoning compile option. It
yielded identical output to patched version without this option as well
as to current git head; I used Alexander Noe's AVI-Mux GUI 
(http://www.alexander-noe.com/video/amg/) to create files using Xiph
lacing to test this on.
I unfortunately couldn't make Clang's MemorySanitizer or its
AddressSanitizer run under MinGW64.
 libavformat/matroskadec.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 3b8ddc5ecb..4dd933ef74 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -2814,7 +2814,7 @@ static int matroska_parse_laces(MatroskaDemuxContext *matroska, uint8_t **buf,
 
     if (!type) {
         *laces    = 1;
-        *lace_buf = av_mallocz(sizeof(int));
+        *lace_buf = av_malloc(sizeof(**lace_buf));
         if (!*lace_buf)
             return AVERROR(ENOMEM);
 
@@ -2826,7 +2826,7 @@ static int matroska_parse_laces(MatroskaDemuxContext *matroska, uint8_t **buf,
     *laces    = *data + 1;
     data     += 1;
     size     -= 1;
-    lace_size = av_mallocz(*laces * sizeof(int));
+    lace_size = av_malloc(*laces * sizeof(*lace_size));
     if (!lace_size)
         return AVERROR(ENOMEM);
 
@@ -2836,6 +2836,8 @@ static int matroska_parse_laces(MatroskaDemuxContext *matroska, uint8_t **buf,
         uint8_t temp;
         uint32_t total = 0;
         for (n = 0; res == 0 && n < *laces - 1; n++) {
+            lace_size[n] = 0;
+
             while (1) {
                 if (size <= total) {
                     res = AVERROR_INVALIDDATA;
-- 
2.21.0