linux-kernel - Re: [PATCH] csky: fix syscall_get_arguments() and syscall_set

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Message-ID: <20190330004949.GA15705@guoren-Inspiron-7460>
Date:   Sat, 30 Mar 2019 08:49:49 +0800
From:   Guo Ren <guoren@...nel.org>
To:     "Dmitry V. Levin" <ldv@...linux.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Andy Lutomirski <luto@...capital.net>,
        Will Drewry <wad@...omium.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] csky: fix syscall_get_arguments() and
 syscall_set_arguments()

Thx Dmitry,

It works for me.

Tested-by: Guo Ren <ren_guo@...ky.com>
Acked-by: Guo Ren <ren_guo@...ky.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 <rostedt@...dmis.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Kees Cook <keescook@...omium.org>
> Cc: Andy Lutomirski <luto@...capital.net>
> Cc: Will Drewry <wad@...omium.org>
> Cc: stable@...r.kernel.org # v4.20+
> Signed-off-by: Dmitry V. Levin <ldv@...linux.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