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

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Message-ID: <20190329131514.3e4ec93e@gandalf.local.home>
Date:   Fri, 29 Mar 2019 13:15:14 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Dmitry V. Levin" <ldv@...linux.org>
Cc:     Palmer Dabbelt <palmer@...ive.com>, Ingo Molnar <mingo@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Andy Lutomirski <luto@...capital.net>,
        Will Drewry <wad@...omium.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv: fix syscall_get_arguments() and
 syscall_set_arguments()

On Fri, 29 Mar 2019 20:12:21 +0300
"Dmitry V. Levin" <ldv@...linux.org> wrote:

> RISC-V syscall arguments are located in orig_a0,a1..a5 fields
> of struct pt_regs.
> 
> Due to an off-by-one bug and a bug in pointer arithmetic
> syscall_get_arguments() was reading s3..s7 fields instead of a1..a5.
> Likewise, syscall_set_arguments() was writing s3..s7 fields
> instead of a1..a5.

Should I add this to my series? And then rebase on top of it?

-- Steve

> 
> Fixes: e2c0cdfba7f69 ("RISC-V: User-facing API")
> 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: linux-riscv@...ts.infradead.org
> Cc: stable@...r.kernel.org # v4.15+
> Signed-off-by: Dmitry V. Levin <ldv@...linux.org>
> ---
>  arch/riscv/include/asm/syscall.h | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h
> index bba3da6ef157..6ea9e1804233 100644
> --- a/arch/riscv/include/asm/syscall.h
> +++ b/arch/riscv/include/asm/syscall.h
> @@ -79,10 +79,11 @@ static inline void syscall_get_arguments(struct task_struct *task,
>  	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 syscall_set_arguments(struct task_struct *task,
> @@ -94,10 +95,11 @@ static inline void syscall_set_arguments(struct task_struct *task,
>          if (i == 0) {
>                  regs->orig_a0 = args[0];
>                  args++;
> -                i++;
>                  n--;
> -        }
> -	memcpy(&regs->a1 + i * sizeof(regs->a1), args, n * sizeof(regs->a0));
> +	} else {
> +		i--;
> +	}
> +	memcpy(&regs->a1 + i, args, n * sizeof(regs->a1));
>  }
>  
>  static inline int syscall_get_arch(void)