The stack randomization feature in the Linux kernel before 3.19.1 on 64-bit platforms uses incorrect data types for the results of bitwise left-shift operations, which makes it easier for attackers to bypass the ASLR protection mechanism by predicting the address of the top of the stack, related to the randomizestacktop function in fs/binfmtelf.c and the stackmaxrandom_size function in arch/x86/mm/mmap.c.