libtiff: out-of-bounds read/write with malformed TIFF image in tiff2pdf

LibTIFF 4.0.3 allows remote attackers to cause a denial of service out-of-bounds write or possibly have unspecified other impact via a crafted TIFF image, as demonstrated by failure of tifnext.c to verify that the BitsPerSample value is 2, and the t2psamplelabsignedtounsigned function in tiff2pdf...