linux-kernel - Re: [PATCH 2/3] MIPS: signal: Return immediately if call fails

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Date:   Sat, 18 Dec 2021 14:08:10 +0000
From:   Jiaxun Yang <jiaxun.yang@...goat.com>
To:     Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     Xuefeng Li <lixuefeng@...ngson.cn>, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] MIPS: signal: Return immediately if call fails



在 2021/12/18 3:23, Tiezhu Yang 写道:
> When debug sigaltstack(), copy_siginfo_to_user() fails first in
> setup_rt_frame() if the alternate signal stack is too small, so
> it should return immediately if call fails, no need to call the
> following functions.

Hi Tiezhu,

Thanks for your patch.
If we are doing so I see no reason for keeping the err variable.
Just

if (copy_siginfo_to_user(&frame->rs_info, &ksig->info))
     return -EFAULT;

seems much more clear.

Thanks.

- Jiaxun

>
> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
> ---
>   arch/mips/kernel/signal.c | 25 +++++++++++++++++++------
>   1 file changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
> index c1632e8..4cd3969 100644
> --- a/arch/mips/kernel/signal.c
> +++ b/arch/mips/kernel/signal.c
> @@ -761,15 +761,28 @@ static int setup_rt_frame(void *sig_return, struct ksignal *ksig,
>   		return -EFAULT;
>   
>   	/* Create siginfo.  */
> -	err |= copy_siginfo_to_user(&frame->rs_info, &ksig->info);
> +	err = copy_siginfo_to_user(&frame->rs_info, &ksig->info);
> +	if (err)
> +		return -EFAULT;
>   
>   	/* Create the ucontext.	 */
> -	err |= __put_user(0, &frame->rs_uc.uc_flags);
> -	err |= __put_user(NULL, &frame->rs_uc.uc_link);
> -	err |= __save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
> -	err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
> -	err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
> +	err = __put_user(0, &frame->rs_uc.uc_flags);
> +	if (err)
> +		return -EFAULT;
> +
> +	err = __put_user(NULL, &frame->rs_uc.uc_link);
> +	if (err)
> +		return -EFAULT;
> +
> +	err = __save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
> +	if (err)
> +		return -EFAULT;
> +
> +	err = setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
> +	if (err)
> +		return -EFAULT;
>   
> +	err = __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
>   	if (err)
>   		return -EFAULT;
>