static unsigned char *DecodeImage(Image *blob,Image *image,
  size_t bytes_per_line,const unsigned int bits_per_pixel,size_t *extent)
{
  MagickSizeType
    number_pixels;

  register ssize_t
    i;

  register unsigned char
    *p,
    *q;

  size_t
    bytes_per_pixel,
    length,
    row_bytes,
    scanline_length,
    width;

  ssize_t
    count,
    j,
    y;

  unsigned char
    *pixels,
    *scanline;

  /*
    Determine pixel buffer size.
  */
  if (bits_per_pixel <= 8)
    bytes_per_line&=0x7fff;
  width=image->columns;
  bytes_per_pixel=1;
  if (bits_per_pixel == 16)
    {
      bytes_per_pixel=2;
      width*=2;
    }
  else
    if (bits_per_pixel == 32)
      width*=image->matte != MagickFalse ? 4 : 3;
  if (bytes_per_line == 0)
    bytes_per_line=width;
  row_bytes=(size_t) (image->columns | 0x8000);
  if (image->storage_class == DirectClass)
    row_bytes=(size_t) ((4*image->columns) | 0x8000);
  /*
    Allocate pixel and scanline buffer.
  */
  pixels=(unsigned char *) AcquireQuantumMemory(image->rows,row_bytes*
    sizeof(*pixels));
  if (pixels == (unsigned char *) NULL)
    return((unsigned char *) NULL);
  *extent=row_bytes*image->rows*sizeof(*pixels);
  (void) ResetMagickMemory(pixels,0,*extent);
  scanline=(unsigned char *) AcquireQuantumMemory(row_bytes,2*
    sizeof(*scanline));
  if (scanline == (unsigned char *) NULL)
    return((unsigned char *) NULL);
  if (bytes_per_line < 8)
    {
      /*
        Pixels are already uncompressed.
      */
      for (y=0; y < (ssize_t) image->rows; y++)
      {
        q=pixels+y*width;
        number_pixels=bytes_per_line;
        count=ReadBlob(blob,(size_t) number_pixels,scanline);
        (void) count;
        p=ExpandBuffer(scanline,&number_pixels,bits_per_pixel);
        if ((q+number_pixels) > (pixels+(*extent)))
          {
            (void) ThrowMagickException(&image->exception,GetMagickModule(),
              CorruptImageError,"UnableToUncompressImage","`%s'",
              image->filename);
            break;
          }
        (void) CopyMagickMemory(q,p,(size_t) number_pixels);
      }
      scanline=(unsigned char *) RelinquishMagickMemory(scanline);
      return(pixels);
    }
  /*
    Uncompress RLE pixels into uncompressed pixel buffer.
  */
  for (y=0; y < (ssize_t) image->rows; y++)
  {
    q=pixels+y*width;
    if (bytes_per_line > 200)
      scanline_length=ReadBlobMSBShort(blob);
    else
      scanline_length=1UL*ReadBlobByte(blob);
    if (scanline_length >= row_bytes)
      {
        (void) ThrowMagickException(&image->exception,GetMagickModule(),
          CorruptImageError,"UnableToUncompressImage","`%s'",image->filename);
        break;
      }
    count=ReadBlob(blob,scanline_length,scanline);
    for (j=0; j < (ssize_t) scanline_length; )
      if ((scanline[j] & 0x80) == 0)
        {
          length=(size_t) ((scanline[j] & 0xff)+1);
          number_pixels=length*bytes_per_pixel;
          p=ExpandBuffer(scanline+j+1,&number_pixels,bits_per_pixel);
          if ((q-pixels+number_pixels) <= *extent)
            (void) CopyMagickMemory(q,p,(size_t) number_pixels);
          q+=number_pixels;
          j+=(ssize_t) (length*bytes_per_pixel+1);
        }
      else
        {
          length=(size_t) (((scanline[j] ^ 0xff) & 0xff)+2);
          number_pixels=bytes_per_pixel;
          p=ExpandBuffer(scanline+j+1,&number_pixels,bits_per_pixel);
          for (i=0; i < (ssize_t) length; i++)
          {
            if ((q-pixels+number_pixels) <= *extent)
              (void) CopyMagickMemory(q,p,(size_t) number_pixels);
            q+=number_pixels;
          }
          j+=(ssize_t) bytes_per_pixel+1;
        }
  }
  scanline=(unsigned char *) RelinquishMagickMemory(scanline);
  return(pixels);
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.