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Date: Mon, 5 Jun 2017 14:37:45 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: zhongjiang <zhongjiang@huawei.com>
Cc: akpm@linux-foundation.org, stsp@list.ru, Waiman.Long@hpe.com,
        mingo@kernel.org, mhocko@kernel.org, vbabka@suse.cz,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org, qiuxishi@huawei.com
Subject: Re: [PATCH] signal: Avoid undefined behaviour in kill_something_info
Message-ID: <20170605123744.GA9807@redhat.com>
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On 06/05, zhongjiang wrote:
>
>  static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
>  {
> -	int ret;
> +	int ret, vpid;
>  
>  	if (pid > 0) {
>  		rcu_read_lock();
> @@ -1395,8 +1395,12 @@ static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
>  
>  	read_lock(&tasklist_lock);
>  	if (pid != -1) {
> +		if (pid == INT_MIN)
> +			vpid = INT_MAX;

Well, this probably needs a comment to explain that this is just "avoid ub".

And if we really want the fix, to me

	if (pid == INT_MIN)
		return -ESRCH;

at the start makes more sense...

Oleg.