Did you read the manual?
http://www.libpng.org/pub/png/libpng-manual.txt
Here's what they have as an example.
Code:
if (height > PNG_UINT_32_MAX/png_sizeof(png_byte))
png_error (png_ptr,
"Image is too tall to process in memory");
if (width > PNG_UINT_32_MAX/pixel_size)
png_error (png_ptr,
"Image is too wide to process in memory");
row_pointers = png_malloc(png_ptr,
height*png_sizeof(png_bytep));
for (int i=0; i<height, i++)
row_pointers[i]=NULL; /* security precaution */
for (int i=0; i<height, i++)
row_pointers[i]=png_malloc(png_ptr,
width*pixel_size);
png_set_rows(png_ptr, info_ptr, &row_pointers);
Your row_pointers are basically garbage.