avutil/imgutils: add utility to get plane sizes

This utility helps avoid undefined behavior when doing things like
checking how much memory we need to allocate for an image before we have
allocated a buffer.

Signed-off-by: Brian Kim <bkkim@google.com>
Signed-off-by: James Almer <jamrial@gmail.com>

doc/APIchanges

@@ -15,6 +15,9 @@ libavutil:     2017-10-21
 
 API changes, most recent first:
 
+2020-07-xx - xxxxxxxxxx - lavu 56.56.100 - imgutils.h
+  Add av_image_fill_plane_sizes().
+
 2020-07-xx - xxxxxxxxxx - lavc 58.96.100 - packet.h
   Add AV_PKT_DATA_S12M_TIMECODE.
 

libavutil/imgutils.c

@@ -108,45 +108,69 @@ int av_image_fill_linesizes(int linesizes[4], enum AVPixelFormat pix_fmt, int wi
     return 0;
 }
 
-int av_image_fill_pointers(uint8_t *data[4], enum AVPixelFormat pix_fmt, int height,
+int av_image_fill_plane_sizes(size_t sizes[4], enum AVPixelFormat pix_fmt,
-                           uint8_t *ptr, const int linesizes[4])
+                              int height, const ptrdiff_t linesizes[4])
 {
-    int i, total_size, size[4] = { 0 }, has_plane[4] = { 0 };
+    int i, has_plane[4] = { 0 };
 
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
-    memset(data     , 0, sizeof(data[0])*4);
+    memset(sizes    , 0, sizeof(sizes[0])*4);
 
     if (!desc || desc->flags & AV_PIX_FMT_FLAG_HWACCEL)
         return AVERROR(EINVAL);
 
-    data[0] = ptr;
+    if (linesizes[0] > SIZE_MAX / height)
-    if (linesizes[0] > (INT_MAX - 1024) / height)
         return AVERROR(EINVAL);
-    size[0] = linesizes[0] * height;
+    sizes[0] = linesizes[0] * (size_t)height;
 
     if (desc->flags & AV_PIX_FMT_FLAG_PAL ||
         desc->flags & FF_PSEUDOPAL) {
-        data[1] = ptr + size[0]; /* palette is stored here as 256 32 bits words */
+        sizes[1] = 256 * 4; /* palette is stored here as 256 32 bits words */
-        return size[0] + 256 * 4;
+        return 0;
     }
 
     for (i = 0; i < 4; i++)
         has_plane[desc->comp[i].plane] = 1;
 
-    total_size = size[0];
     for (i = 1; i < 4 && has_plane[i]; i++) {
         int h, s = (i == 1 || i == 2) ? desc->log2_chroma_h : 0;
-        data[i] = data[i-1] + size[i-1];
         h = (height + (1 << s) - 1) >> s;
-        if (linesizes[i] > INT_MAX / h)
+        if (linesizes[i] > SIZE_MAX / h)
             return AVERROR(EINVAL);
-        size[i] = h * linesizes[i];
+        sizes[i] = (size_t)h * linesizes[i];
-        if (total_size > INT_MAX - size[i])
-            return AVERROR(EINVAL);
-        total_size += size[i];
     }
 
-    return total_size;
+    return 0;
+}
+
+int av_image_fill_pointers(uint8_t *data[4], enum AVPixelFormat pix_fmt, int height,
+                           uint8_t *ptr, const int linesizes[4])
+{
+    int i, ret;
+    ptrdiff_t linesizes1[4];
+    size_t sizes[4];
+
+    for (i = 0; i < 4; i++)
+        linesizes1[i] = linesizes[i];
+
+    ret = av_image_fill_plane_sizes(sizes, pix_fmt, height, linesizes1);
+    if (ret < 0)
+        return ret;
+
+    ret = 0;
+    for (i = 0; i < 4; i++) {
+        if (sizes[i] > INT_MAX - ret)
+            return AVERROR(EINVAL);
+        ret += sizes[i];
+    }
+
+    memset(data , 0, sizeof(data[0])*4);
+
+    data[0] = ptr;
+    for (i = 1; i < 4 && sizes[i - 1] > 0; i++)
+        data[i] = data[i - 1] + sizes[i - 1];
+
+    return ret;
 }
 
 int avpriv_set_systematic_pal2(uint32_t pal[256], enum AVPixelFormat pix_fmt)
@@ -194,6 +218,8 @@ int av_image_alloc(uint8_t *pointers[4], int linesizes[4],
 {
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
     int i, ret;
+    ptrdiff_t linesizes1[4];
+    size_t total_size, sizes[4];
     uint8_t *buf;
 
     if (!desc)
@@ -204,12 +230,20 @@ int av_image_alloc(uint8_t *pointers[4], int linesizes[4],
     if ((ret = av_image_fill_linesizes(linesizes, pix_fmt, align>7 ? FFALIGN(w, 8) : w)) < 0)
         return ret;
 
-    for (i = 0; i < 4; i++)
+    for (i = 0; i < 4; i++) {
         linesizes[i] = FFALIGN(linesizes[i], align);
+        linesizes1[i] = linesizes[i];
+    }
 
-    if ((ret = av_image_fill_pointers(pointers, pix_fmt, h, NULL, linesizes)) < 0)
+    if ((ret = av_image_fill_plane_sizes(sizes, pix_fmt, h, linesizes1)) < 0)
         return ret;
-    buf = av_malloc(ret + align);
+    total_size = align;
+    for (i = 0; i < 4; i++) {
+        if (total_size > SIZE_MAX - sizes[i])
+            return AVERROR(EINVAL);
+        total_size += sizes[i];
+    }
+    buf = av_malloc(total_size);
     if (!buf)
         return AVERROR(ENOMEM);
     if ((ret = av_image_fill_pointers(pointers, pix_fmt, h, buf, linesizes)) < 0) {
@@ -220,6 +254,7 @@ int av_image_alloc(uint8_t *pointers[4], int linesizes[4],
         avpriv_set_systematic_pal2((uint32_t*)pointers[1], pix_fmt);
         if (align < 4) {
             av_log(NULL, AV_LOG_ERROR, "Formats with a palette require a minimum alignment of 4\n");
+            av_free(buf);
             return AVERROR(EINVAL);
         }
     }
@@ -431,9 +466,10 @@ int av_image_fill_arrays(uint8_t *dst_data[4], int dst_linesize[4],
 int av_image_get_buffer_size(enum AVPixelFormat pix_fmt,
                              int width, int height, int align)
 {
-    uint8_t *data[4];
+    int ret, i;
     int linesize[4];
-    int ret;
+    ptrdiff_t aligned_linesize[4];
+    size_t sizes[4];
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
     if (!desc)
         return AVERROR(EINVAL);
@@ -446,8 +482,24 @@ int av_image_get_buffer_size(enum AVPixelFormat pix_fmt,
     if (desc->flags & FF_PSEUDOPAL)
         return FFALIGN(width, align) * height;
 
-    return av_image_fill_arrays(data, linesize, NULL, pix_fmt,
+    ret = av_image_fill_linesizes(linesize, pix_fmt, width);
-                                width, height, align);
+    if (ret < 0)
+        return ret;
+
+    for (i = 0; i < 4; i++)
+        aligned_linesize[i] = FFALIGN(linesize[i], align);
+
+    ret = av_image_fill_plane_sizes(sizes, pix_fmt, height, aligned_linesize);
+    if (ret < 0)
+        return ret;
+
+    ret = 0;
+    for (i = 0; i < 4; i++) {
+        if (sizes[i] > INT_MAX - ret)
+            return AVERROR(EINVAL);
+        ret += sizes[i];
+    }
+    return ret;
 }
 
 int av_image_copy_to_buffer(uint8_t *dst, int dst_size,

libavutil/imgutils.h

@@ -67,6 +67,20 @@ int av_image_get_linesize(enum AVPixelFormat pix_fmt, int width, int plane);
  */
 int av_image_fill_linesizes(int linesizes[4], enum AVPixelFormat pix_fmt, int width);
 
+/**
+ * Fill plane sizes for an image with pixel format pix_fmt and height height.
+ *
+ * @param size the array to be filled with the size of each image plane
+ * @param linesizes the array containing the linesize for each
+ *        plane, should be filled by av_image_fill_linesizes()
+ * @return >= 0 in case of success, a negative error code otherwise
+ *
+ * @note The linesize parameters have the type ptrdiff_t here, while they are
+ *       int for av_image_fill_linesizes().
+ */
+int av_image_fill_plane_sizes(size_t size[4], enum AVPixelFormat pix_fmt,
+                              int height, const ptrdiff_t linesizes[4]);
+
 /**
  * Fill plane data pointers for an image with pixel format pix_fmt and
  * height height.

libavutil/version.h

@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  56
-#define LIBAVUTIL_VERSION_MINOR  55
+#define LIBAVUTIL_VERSION_MINOR  56
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \