linux-kernel - Re: [PATCH] signals: work around random wakeups in sigsuspend()

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: <20160225031852.GV17997@ZenIV.linux.org.uk>
Date:	Thu, 25 Feb 2016 03:18:52 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Sasha Levin <sasha.levin@...cle.com>, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, mingo@...nel.org,
	peterz@...radead.org
Subject: Re: [PATCH] signals: work around random wakeups in sigsuspend()

On Mon, Jan 25, 2016 at 08:09:15PM +0100, Oleg Nesterov wrote:
> On 01/25, Sasha Levin wrote:
> >
> > A random wakeup can get us out of sigsuspend() without TIF_SIGPENDING
> > being set.
> 
> and TIF_RESTORE_SIGMASK is just wrong in this case. I'd say this is the
> bugfix, not work-around ;)
> 
> > Avoid that by making sure we were signaled, like sys_pause() does.
> >
> > Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
> 
> Acked-by: Oleg Nesterov <oleg@...hat.com>
> 
> Thanks Sasha.

Out of curiousity - where did that stray wakeup come from?  PTRACE_KILL
used to trigger those, but that got fixed.  How does one trigger that
kind of bugs on the current kernels?