linux-kernel - Re: [PATCH 07/14] uaccess: generalize access

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Date:   Mon, 14 Feb 2022 20:25:24 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Christoph Hellwig <hch@....de>,
        linux-arch <linux-arch@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        Linux API <linux-api@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
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Subject: Re: [PATCH 07/14] uaccess: generalize access_ok()

On Mon, Feb 14, 2022 at 6:15 PM Al Viro <viro@...iv.linux.org.uk> wrote:
>
> On Mon, Feb 14, 2022 at 05:34:45PM +0100, Arnd Bergmann wrote:
>
> > diff --git a/arch/csky/kernel/signal.c b/arch/csky/kernel/signal.c
> > index c7b763d2f526..8867ddf3e6c7 100644
> > --- a/arch/csky/kernel/signal.c
> > +++ b/arch/csky/kernel/signal.c
> > @@ -136,7 +136,7 @@ static inline void __user *get_sigframe(struct ksignal *ksig,
> >  static int
> >  setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
> >  {
> > -     struct rt_sigframe *frame;
> > +     struct rt_sigframe __user *frame;
> >       int err = 0;
> >
> >       frame = get_sigframe(ksig, regs, sizeof(*frame));
>
> Minor nit: might make sense to separate annotations (here, on nios2, etc.) from the rest...

Done.

> > -}
> > -
> > -static inline int access_ok(const void __user * addr, unsigned long size)
> > -{
> > -     return 1;
> > -}
> > +#define __range_not_ok(addr, size, limit) (!__access_ok(addr, size))
>
> is really wrong.  For sparc64, access_ok() should always be true.
> This __range_not_ok() thing is used *only* for valid_user_frame() in
> arch/sparc/kernel/perf_event.c - it's not a part of normal access_ok()
> there.
>
> sparc64 has separate address spaces for kernel and for userland; access_ok()
> had never been useful there.

Ok, fixed as well now. I had the access_ok() bit right, the definition just
moved around here so it comes before the #include, but I missed the
bit about __range_not_ok(), which I have now reverted back to the
correct version in my tree.

        Arnd