linux-kernel - Re: [PATCH v2 2/3] MIPS: signal: Return immediately if call fails

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Date:   Sun, 2 Jan 2022 14:31:22 +0100
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Tiezhu Yang <yangtiezhu@...ngson.cn>
Cc:     Xuefeng Li <lixuefeng@...ngson.cn>, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] MIPS: signal: Return immediately if call fails

On Mon, Dec 20, 2021 at 12:27:39PM +0800, Tiezhu Yang wrote:
> 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.
> 
> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
> ---
>  arch/mips/kernel/signal.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
> index c1632e8..5bce782 100644
> --- a/arch/mips/kernel/signal.c
> +++ b/arch/mips/kernel/signal.c
> @@ -754,23 +754,25 @@ static int setup_rt_frame(void *sig_return, struct ksignal *ksig,
>  			  struct pt_regs *regs, sigset_t *set)
>  {
>  	struct rt_sigframe __user *frame;
> -	int err = 0;
>  
>  	frame = get_sigframe(ksig, regs, sizeof(*frame));
>  	if (!access_ok(frame, sizeof (*frame)))
>  		return -EFAULT;
>  
>  	/* Create siginfo.  */
> -	err |= copy_siginfo_to_user(&frame->rs_info, &ksig->info);
> +	if (copy_siginfo_to_user(&frame->rs_info, &ksig->info))
> +		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));
> -
> -	if (err)
> +	if (__put_user(0, &frame->rs_uc.uc_flags))
> +		return -EFAULT;
> +	if (__put_user(NULL, &frame->rs_uc.uc_link))
> +		return -EFAULT;
> +	if (__save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]))
> +		return -EFAULT;
> +	if (setup_sigcontext(regs, &frame->rs_uc.uc_mcontext))
> +		return -EFAULT;
> +	if (__copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set)))
>  		return -EFAULT;
>  
>  	/*
> -- 
> 2.1.0

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]