linux-kernel - RE: RCU bug with v3.17-rc3 ?

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]

Date:	Mon, 13 Oct 2014 09:11:34 +0000
From:	David Laight <David.Laight@...LAB.COM>
To:	'Nathan Lynch' <Nathan_Lynch@...tor.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>
CC:	Felipe Balbi <balbi@...com>, Rik van Riel <riel@...hat.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Tony Lindgren <tony@...mide.com>,
	Linux USB Mailing List <linux-usb@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"josh@...htriplett.org" <josh@...htriplett.org>,
	Rabin Vincent <rabin@....in>,
	Alan Stern <stern@...land.harvard.edu>,
	Johannes Weiner <hannes@...xchg.org>,
	"Sasha Levin" <sasha.levin@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux ARM Kernel Mailing List 
	<linux-arm-kernel@...ts.infradead.org>
Subject: RE: RCU bug with v3.17-rc3 ?

From: Nathan Lynch
> On 10/10/2014 11:25 AM, Russell King - ARM Linux wrote:
> >
> > Right, so GCC 4.8.{1,2} are totally unsuitable for kernel building (and
> > it seems that this has been known about for some time.)
> 
> Looking at http://gcc.gnu.org/PR58854 it seems that all 4.8.x for x < 3
> are affected, as well as 4.9.0.
> 
> > We can blacklist these GCC versions quite easily.  We already have GCC
> > 3.3 blacklisted, and it's trivial to add others.  I would want to include
> > some proper details about the bug, just like the other existing entries
> > we already have in asm-offsets.c, where we name the functions that the
> > compiler is known to break where appropriate.
> 
> Before blacklisting anything, it's worth considering that simple version
> checks would break existing pre-4.8.3 compilers that have been patched
> for PR58854.  It looks like Yocto and Buildroot issued releases with
> patched 4.8.2 compilers well before the (fixed) 4.8.3 release.  I think
> the most we can reasonably do without breaking some correctly-behaving
> toolchains is to emit a warning.

Is it possible to compile a small code fragment and check the generated
code for the bug?
Possibly predicated on the broken version number to avoid false positives.

	David



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/