linux-kernel - Re: [PATCH/RFC v5 4/5]: core: Add dump device to call on oopses and panics

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: <1259566071.7518.48.camel@localhost>
Date:	Mon, 30 Nov 2009 09:27:51 +0200
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Jörn Engel <joern@...fs.org>
Cc:	Simon Kagstrom <simon.kagstrom@...insight.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-mtd <linux-mtd@...ts.infradead.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Koskinen Aaro (Nokia-D/Helsinki)" <aaro.koskinen@...ia.com>,
	Ingo Molnar <mingo@...e.hu>,
	David Woodhouse <dwmw2@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH/RFC v5 4/5]: core: Add dump device to call on oopses
 and panics

On Thu, 2009-11-26 at 10:36 +0100, Jörn Engel wrote:
> Just stumbled across this patch.
> 
> On Tue, 13 October 2009 15:22:35 +0200, Simon Kagstrom wrote:
> > +void dump_kmsg(int panic)
> > +{
> > +	unsigned long len = ACCESS_ONCE(log_end);
> > +	struct dump_device *dump;
> > +	const char *s1, *s2;
> > +	unsigned long l1, l2;
> > +
> > +	s1 = "";
> > +	l1 = 0;
> > +	s2 = log_buf;
> > +	l2 = len;
> > +
> > +	/* Have we rotated around the circular buffer? */
> > +	if (len > log_buf_len) {
> 
> I believe this bit is wrong.  log_end is an unsigned int, so it can
> wrap relatively quickly.  If log_end just wrapped to 0 and dump_kmsg is
> called, the amount of printk buffer stored appears to be 0 as well.

To me it looks like 'log_end' is not supposed to wrap. What makes you
think it can? In which cases it can?

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)

--
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/