Re: [PATCH] csky: fix syscall_get_arguments() and syscall_set_arguments()

[Guo Ren]

Thx Dmitry,

It works for me.

Tested-by: Guo Ren <ren_...@c-sky.com>
Acked-by: Guo Ren <ren_...@c-sky.com>

On Fri, Mar 29, 2019 at 08:12:30PM +0300, Dmitry V. Levin wrote:
> C-SKY syscall arguments are located in orig_a0,a1,a2,a3,regs[0],regs[1]
> fields of struct pt_regs.
> 
> Due to an off-by-one bug and a bug in pointer arithmetic
> syscall_get_arguments() was reading orig_a0,regs[1..5] fields instead.
> Likewise, syscall_set_arguments() was writing orig_a0,regs[1..5] fields
> instead.
> 
> Fixes: 4859bfca11c7d ("csky: System Call")
> Cc: Steven Rostedt <rost...@goodmis.org>
> Cc: Ingo Molnar <mi...@redhat.com>
> Cc: Kees Cook <keesc...@chromium.org>
> Cc: Andy Lutomirski <l...@amacapital.net>
> Cc: Will Drewry <w...@chromium.org>
> Cc: sta...@vger.kernel.org # v4.20+
> Signed-off-by: Dmitry V. Levin <l...@altlinux.org>
> ---
>  arch/csky/include/asm/syscall.h | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/csky/include/asm/syscall.h b/arch/csky/include/asm/syscall.h
> index d637445737b7..9a9cd81e66c1 100644
> --- a/arch/csky/include/asm/syscall.h
> +++ b/arch/csky/include/asm/syscall.h
> @@ -49,10 +49,11 @@ syscall_get_arguments(struct task_struct *task, struct 
> pt_regs *regs,
>       if (i == 0) {
>               args[0] = regs->orig_a0;
>               args++;
> -             i++;
>               n--;
> +     } else {
> +             i--;
>       }
> -     memcpy(args, &regs->a1 + i * sizeof(regs->a1), n * sizeof(args[0]));
> +     memcpy(args, &regs->a1 + i, n * sizeof(args[0]));
>  }
>  
>  static inline void
> @@ -63,10 +64,11 @@ syscall_set_arguments(struct task_struct *task, struct 
> pt_regs *regs,
>       if (i == 0) {
>               regs->orig_a0 = args[0];
>               args++;
> -             i++;
>               n--;
> +     } else {
> +             i--;
>       }
> -     memcpy(&regs->a1 + i * sizeof(regs->a1), args, n * sizeof(regs->a0));
> +     memcpy(&regs->a1 + i, args, n * sizeof(regs->a1));
>  }
>  
>  static inline int
> -- 
> ldv