linux-kernel - Re: [4.1.x -- 4.6.x and probably HEAD] Reproducible unprivileged panic/TLB BUG on sparc via a stack-protected rt_sigaction() ka_restorer, courtesy of the glibc testsuite

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Date:	Fri, 27 May 2016 14:43:01 +0100
From:	Nick Alcock <nix@...eri.org.uk>
To:	John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Cc:	linux-kernel@...r.kernel.org,
	Sparc kernel list <sparclinux@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Florian Weimer <fweimer@...hat.com>,
	"Jose E. Marchesi" <jose.marchesi@...cle.com>
Subject: Re: [4.1.x -- 4.6.x and probably HEAD] Reproducible unprivileged panic/TLB BUG on sparc via a stack-protected rt_sigaction() ka_restorer, courtesy of the glibc testsuite

On 27 May 2016, John Paul Adrian Glaubitz outgrape:

> Hi Nick!
>
> On 05/27/2016 03:19 PM, Nick Alcock wrote:
>> So I've been working on a patch series (see below) that applies GCC's
>> -fstack-protector{-all,-strong} to almost all of glibc bar the dynamic
>> linker. In trying to upstream it, one review commenter queried one
>> SPARC-specific patch in the series; the absence of this patch triggers a
>> BUG in the SPARC kernel when glibc is tested as an unprivileged user, on
>> all versions tested from Oracle UEK 4.1 right up to 4.6.0, at least on
>> the ldoms I have access to and presumably on bare hardware too.
>
> I apologize for hijacking this thread but since you are mentioning glibc,
> there are actually a couple of tests in the glibc testsuite [1].

At least one of those failures is spurious:

FAIL: nptl/tst-cond11
original exit status 1
clock = 0
Timed out: killed the child process

You want to pass in a higher TIMEOUTFACTOR to the make check run, and
that problem at least should go away. (The TIMEOUTFACTOR you need
depends on how sluggish your test machine is.)