[libpng16] Moved chunk-length check into a png_check_chunk_length() private

function (Suggested by Max Stepin).

1 files changed, 39 insertions, 31 deletions

diff --git a/pngrutil.c b/pngrutil.c
index 476837700..b744a51d9 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -157,7 +157,6 @@ png_read_chunk_header(png_structrp png_ptr)
 {
    png_byte buf[8];
    png_uint_32 length;
-   png_alloc_size_t limit = PNG_UINT_31_MAX;
 
 #ifdef PNG_IO_STATE_SUPPORTED
    png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
@@ -183,36 +182,7 @@ png_read_chunk_header(png_structrp png_ptr)
    png_check_chunk_name(png_ptr, png_ptr->chunk_name);
 
    /* Check for too-large chunk length */
-   if (png_ptr->chunk_name != png_IDAT)
-   {
-# ifdef PNG_SET_USER_LIMITS_SUPPORTED
-      if (png_ptr->user_chunk_malloc_max > 0 &&
-          png_ptr->user_chunk_malloc_max < limit)
-         limit = png_ptr->user_chunk_malloc_max;
-# elif PNG_USER_CHUNK_MALLOC_MAX > 0
-      if (PNG_USER_CHUNK_MALLOC_MAX < limit)
-         limit = PNG_USER_CHUNK_MALLOC_MAX;
-# endif
-   }
-   else
-   {
-      size_t row_factor =
-         (png_ptr->width * png_ptr->channels * (png_ptr->bit_depth > 8? 2: 1)
-          + 1 + (png_ptr->interlaced? 6: 0));
-      if (png_ptr->height > PNG_UINT_32_MAX/row_factor)
-         limit=PNG_UINT_31_MAX;
-      else
-         limit = png_ptr->height * row_factor;
-      limit += 6 + 5*(limit/32566+1); /* zlib+deflate overhead */
-      limit=limit < PNG_UINT_31_MAX? limit : PNG_UINT_31_MAX;
-   }
-
-   if (length > limit)
-   {
-      png_debug2(0," length = %lu, limit = %lu",
-         (unsigned long)length,(unsigned long)limit);
-      png_chunk_error(png_ptr, "chunk data is too large");
-   }
+   png_check_chunk_length(png_ptr, png_ptr->chunk_name, length);
 
 #ifdef PNG_IO_STATE_SUPPORTED
    png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
@@ -3134,6 +3104,44 @@ png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
    }
 }
 
+void /* PRIVATE */
+png_check_chunk_length(png_structrp png_ptr, png_uint_32 chunk_name,
+   png_uint_32 length)
+{
+   png_alloc_size_t limit = PNG_UINT_31_MAX;
+
+   if (png_ptr->chunk_name != png_IDAT)
+   {
+# ifdef PNG_SET_USER_LIMITS_SUPPORTED
+      if (png_ptr->user_chunk_malloc_max > 0 &&
+          png_ptr->user_chunk_malloc_max < limit)
+         limit = png_ptr->user_chunk_malloc_max;
+# elif PNG_USER_CHUNK_MALLOC_MAX > 0
+      if (PNG_USER_CHUNK_MALLOC_MAX < limit)
+         limit = PNG_USER_CHUNK_MALLOC_MAX;
+# endif
+   }
+   else
+   {
+      size_t row_factor =
+         (png_ptr->width * png_ptr->channels * (png_ptr->bit_depth > 8? 2: 1)
+          + 1 + (png_ptr->interlaced? 6: 0));
+      if (png_ptr->height > PNG_UINT_32_MAX/row_factor)
+         limit=PNG_UINT_31_MAX;
+      else
+         limit = png_ptr->height * row_factor;
+      limit += 6 + 5*(limit/32566+1); /* zlib+deflate overhead */
+      limit=limit < PNG_UINT_31_MAX? limit : PNG_UINT_31_MAX;
+   }
+
+   if (length > limit)
+   {
+      png_debug2(0," length = %lu, limit = %lu",
+         (unsigned long)length,(unsigned long)limit);
+      png_chunk_error(png_ptr, "chunk data is too large");
+   }
+}
+
 /* Combines the row recently read in with the existing pixels in the row.  This
  * routine takes care of alpha and transparency if requested.  This routine also
  * handles the two methods of progressive display of interlaced images,