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Date: Thu, 18 Apr 2024 18:38:11 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Anna-Maria Behnsen <anna-maria@linutronix.de>,
	Frederic Weisbecker <frederic@kernel.org>,
	John Stultz <jstultz@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>, Stephen Boyd <sboyd@kernel.org>,
	Eric Biederman <ebiederm@xmission.com>
Subject: Re: [patch V2 26/50] signal: Get rid of resched_timer logic
Message-ID: <20240418163811.GA23440@redhat.com>
References: <20240410164558.316665885@linutronix.de>
 <20240410165552.572304080@linutronix.de>
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User-Agent: Mutt/1.5.24 (2015-08-30)

On 04/11, Thomas Gleixner wrote:
>
> There is no reason for handing the *resched pointer argument through
> several functions just to check whether the signal is related to a self
> rearming posix timer.

Agreed, these changes looks good to me.

But,

> SI_TIMER is only used by the posix timer code and cannot be queued from
> user space.

Why? I think sigqueueinfo() can certainly use si_code = SI_TIMER, so

> @@ -1011,6 +1001,9 @@ static int __send_signal_locked(int sig,
>  
>  	lockdep_assert_held(&t->sighand->siglock);
>  
> +	if (WARN_ON_ONCE(!is_si_special(info) && info->si_code == SI_TIMER))
> +		return 0;

this can be easily triggered by userspace and thus looks wrong.

Oleg.