linux-kernel - Re: [PATCH 0/2] Fatal signal handing within uaccess faults

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Message-ID: <20170711151053.GG2681@leverpostej>
Date:   Tue, 11 Jul 2017 16:10:53 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     linux-arm-kerne@...ts.infradead.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        James Morse <james.morse@....com>,
        Laura Abbott <labbott@...hat.com>,
        Russell King <linux@...linux.org.uk>,
        stable <stable@...r.kernel.org>, steve.capper@....com,
        Will Deacon <will.deacon@....com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 0/2] Fatal signal handing within uaccess faults

On Tue, Jul 11, 2017 at 08:04:50AM -0700, Andy Lutomirski wrote:
> On Tue, Jul 11, 2017 at 7:16 AM, Mark Rutland <mark.rutland@....com> wrote:
> > Hi,
> >
> > Arch maintainer tl;dr: most arch fault code doesn't handle fatal signals
> > correctly, allowing unprivileged users to create an unkillable task which can
> > lock up the system. Please check whether your arch is affected.
> 
> I haven't tested for real, but brief inspection of the code suggests
> that x86 is okay.

AFAICT, yes.

As mentioned later on in the message, I beleive it's been ok since
commit:

  26178ec11ef3c6c8 ("x86: mm: consolidate VM_FAULT_RETRY handling")

... and my test-case didn't trigger anything in local testing on my
desktop.

Mark.