libtiff: use of uninitialized memory in putcontig8bitYCbCr21tile and NeXTDecode

The 1 putcontig8bitYCbCr21tile function in tifgetimage.c or 2 NeXTDecode function in tifnext.c in LibTIFF allows remote attackers to cause a denial of service uninitialized memory access via a crafted TIFF image, as demonstrated by libtiff-cvs-1.tif and libtiff-cvs-2.tif...