(tiff2pdf): Heap-based buffer overflow due to improper initialization of T2P context struct pointer

The t2preadtiffinit function in tiff2pdf tools/tiff2pdf.c in LibTIFF 4.0.2 and earlier does not properly initialize the T2P context struct pointer in certain error conditions, which allows context-dependent attackers to cause a denial of service crash and possibly execute arbitrary code via a...