File ImageMagick-CVE-2020-25664.patch of Package ImageMagick.17846

Index: ImageMagick-7.0.7-34/coders/png.c
===================================================================
--- ImageMagick-7.0.7-34.orig/coders/png.c	2020-12-08 17:30:38.835975421 +0100
+++ ImageMagick-7.0.7-34/coders/png.c	2020-12-08 17:41:06.920228237 +0100
@@ -11361,10 +11361,11 @@ static MagickBooleanType WriteOnePNGImag
       (void) LogMagickEvent(CoderEvent,GetMagickModule(),
         "    Allocating %.20g bytes of memory for pixels",(double) rowbytes);
     }
-  pixel_info=AcquireVirtualMemory(rowbytes,sizeof(*ping_pixels));
+  pixel_info=AcquireVirtualMemory(rowbytes+256,sizeof(*ping_pixels));
   if (pixel_info == (MemoryInfo *) NULL)
     png_error(ping,"Allocation of memory for pixels failed");
   ping_pixels=(unsigned char *) GetVirtualMemoryBlob(pixel_info);
+  (void) memset(ping_pixels,0,(rowbytes+256)*sizeof(*ping_pixels));
   /*
     Initialize image scanlines.
   */