Re: [PATCH v2 10/18] m68k: fix access_ok for coldfire

Arnd Bergmann
2022-02-18T09:25:14Z

On Fri, Feb 18, 2022 at 10:00 AM Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> > /* We let the MMU do all checking */
> > -static inline int access_ok(const void __user *addr,
> > +static inline int access_ok(const void __user *ptr,
> > unsigned long size)
> > {
> > + unsigned long limit = TASK_SIZE;
> > + unsigned long addr = (unsigned long)ptr;
> > +
> > /*
> > * XXX: for !CONFIG_CPU_HAS_ADDRESS_SPACES this really needs to check
> > * for TASK_SIZE!
> > + * Removing this helper is probably sufficient.
> > */
>
> Shouldn't the above comment block be removed completely,
> as this is now implemented below?

Yes, obviously. Fixed now.

> > - return 1;
> > + if (IS_ENABLED(CONFIG_CPU_HAS_ADDRESS_SPACES))
> > + return 1;

I just noticed this should have the same change that I made for the
generic version, changed it now to

+ if (IS_ENABLED(CONFIG_CPU_HAS_ADDRESS_SPACES) ||
+ !IS_ENABLED(CONFIG_MMU))

This is gone again after the cleanup patch, when the generic version
is used instead.

> > + return (size <= limit) && (addr <= (limit - size));
> > }
>
> Any pesky compilers that warn (or worse with -Werror) about
> "condition always true" for TASK_SIZE = 0xFFFFFFFFUL?

No, using a local variable avoids this warning.

Arnd