On Wed, Feb 16, 2022 at 2:13 PM Arnd Bergmann <arnd@xxxxxxxxxx> wrote: > + * limit and catch all possible overflows. > + * On architectures with separate user address space (m68k, s390, parisc, > + * sparc64) or those without an MMU, this should always return true. ... > +static inline int __access_ok(const void __user *ptr, unsigned long size) > +{ > + unsigned long limit = user_addr_max(); > + unsigned long addr = (unsigned long)ptr; > + > + if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE)) > + return true; I noticed that I'm missing the check for !CONFIG_MMU here, despite mentioning that in the comment above it. I've added it now. Arnd