Re: [PATCH 07/14] uaccess: generalize access_ok()

Al Viro
2022-02-14T17:15:51Z

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...

This, OTOH,

> diff --git a/arch/sparc/include/asm/uaccess_64.h b/arch/sparc/include/asm/uaccess_64.h
> index 5c12fb46bc61..000bac67cf31 100644
> --- a/arch/sparc/include/asm/uaccess_64.h
> +++ b/arch/sparc/include/asm/uaccess_64.h
...
> -static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
> -{
> - if (__builtin_constant_p(size))
> - return addr > limit - size;
> -
> - addr += size;
> - if (addr < size)
> - return true;
> -
> - return addr > limit;
> -}
> -
> -#define __range_not_ok(addr, size, limit) \
> -({ \
> - __chk_user_ptr(addr); \
> - __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
> -})
> -
> -static inline int __access_ok(const void __user * addr, unsigned long size)
> -{
> - return 1;
> -}
> -
> -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.