lavu/imgutils: add consistency checks to av_image_copy_plane()

Add assertions and abort in case of invalid |dst_linesize| < bytewidth or
|src_linesize| < bytewidth.

Avoid to silently corrupt memory.

libavutil/imgutils.c

@@ -21,6 +21,7 @@
  * misc image utilities
  */
 
+#include "avassert.h"
 #include "common.h"
 #include "imgutils.h"
 #include "internal.h"
@@ -244,6 +245,8 @@ void av_image_copy_plane(uint8_t       *dst, int dst_linesize,
 {
     if (!dst || !src)
         return;
+    av_assert0(abs(src_linesize) >= bytewidth);
+    av_assert0(abs(dst_linesize) >= bytewidth);
     for (;height > 0; height--) {
         memcpy(dst, src, bytewidth);
         dst += dst_linesize;

libavutil/imgutils.h

@@ -99,6 +99,9 @@ int av_image_alloc(uint8_t *pointers[4], int linesizes[4],
  * The first byte of each successive line is separated by *_linesize
  * bytes.
  *
+ * bytewidth must be contained by both absolute values of dst_linesize
+ * and src_linesize, otherwise the function behavior is undefined.
+ *
  * @param dst_linesize linesize for the image plane in dst
  * @param src_linesize linesize for the image plane in src
  */

libavutil/version.h

@@ -76,7 +76,7 @@
 
 #define LIBAVUTIL_VERSION_MAJOR  52
 #define LIBAVUTIL_VERSION_MINOR   9
-#define LIBAVUTIL_VERSION_MICRO 100
+#define LIBAVUTIL_VERSION_MICRO 101
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
                                                LIBAVUTIL_VERSION_MINOR, \