linux-kernel - Re: [RFC PATCH v11 for 4.15 01/24] Restartable sequences system call

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20171116184305.snpudnjdhua2obby@hirez.programming.kicks-ass.net>
Date:   Thu, 16 Nov 2017 19:43:05 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc:     "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Andy Lutomirski <luto@...capital.net>,
        Dave Watson <davejwatson@...com>, linux-kernel@...r.kernel.org,
        linux-api@...r.kernel.org, Paul Turner <pjt@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Russell King <linux@....linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, Andrew Hunter <ahh@...gle.com>,
        Andi Kleen <andi@...stfloor.org>, Chris Lameter <cl@...ux.com>,
        Ben Maurer <bmaurer@...com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Josh Triplett <josh@...htriplett.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [RFC PATCH v11 for 4.15 01/24] Restartable sequences system call

On Tue, Nov 14, 2017 at 03:03:51PM -0500, Mathieu Desnoyers wrote:
> +/*
> + * If parent process has a registered restartable sequences area, the
> + * child inherits. Only applies when forking a process, not a thread. In
> + * case a parent fork() in the middle of a restartable sequence, set the
> + * resume notifier to force the child to retry.
> + */
> +static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags)
> +{
> +	if (clone_flags & CLONE_THREAD) {
> +		t->rseq = NULL;
> +		t->rseq_len = 0;
> +		t->rseq_sig = 0;
> +	} else {
> +		t->rseq = current->rseq;
> +		t->rseq_len = current->rseq_len;
> +		t->rseq_sig = current->rseq_sig;
> +		rseq_set_notify_resume(t);
> +	}
> +}

This hurts my brain... what happens if you fork a multi-threaded
process?

Do we fully inherit the TLS state of the calling thread?