Code: deinterlace_row(png_bytep buffer, png_const_bytep row,
   unsigned int pixel_size, png_uint_32 w, int pass)
{
   /* The inverse of the above, 'row' is part of row 'y' of the output image,
    * in 'buffer'.  The image is 'w' wide and this is pass 'pass', distribute
    * the pixels of row into buffer and return the number written (to allow
    * this to be checked).
    */
   png_uint_32 xin, xout, xstep;
   xout = PNG_PASS_START_COL(pass);
   xstep = 1U<<PNG_PASS_COL_SHIFT(pass);
   for (xin=0; xout<w; xout+=xstep)
   {
      pixel_copy(buffer, xout, row, xin, pixel_size);
      ++xin;
   }
}

Vulnerability Type: +Priv 
CWE ID: 
Summary: Unspecified vulnerability in libpng before 1.6.20, as used in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-07-01, allows attackers to gain privileges via a crafted application, as demonstrated by obtaining Signature or SignatureOrSystem access, aka internal bug 23265085.
Commit Message: DO NOT MERGE Update libpng to 1.6.20

BUG:23265085
Change-Id: I85199805636d771f3597b691b63bc0bf46084833
(cherry picked from commit bbe98b40cda082024b669fa508931042eed18f82)
