On Fri, Jul 21, 2023, at 12:22, Peter Zijlstra wrote: > * futex_parse_waitv - Parse a waitv array from userspace > @@ -207,7 +207,12 @@ static int futex_parse_waitv(struct fute > if ((aux.flags & ~FUTEX2_MASK) || aux.__reserved) > return -EINVAL; > > - if (!(aux.flags & FUTEX2_32)) > + if (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()) { > + if ((aux.flags & FUTEX2_64) == FUTEX2_64) > + return -EINVAL; > + } > + > + if ((aux.flags & FUTEX2_64) != FUTEX2_32) > return -EINVAL; This looks slightly confusing, how about defining another FUTEX2_SIZEMASK (or similar) macro to clarify that "aux.flags & FUTEX2_64" is a mask operation that can match the FUTEX2_{8,16,32,64} values? Arnd