linux-kernel - Re: [PATCH 4/4] [RFC] ipv6: Fix for possible ipv6 seqlock deadlock

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1380223848.3165.207.camel@edumazet-glaptop>
Date:	Thu, 26 Sep 2013 12:30:48 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	John Stultz <john.stultz@...aro.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>
Subject: Re: [PATCH 4/4] [RFC] ipv6: Fix for possible ipv6 seqlock deadlock

On Thu, 2013-09-26 at 11:34 -0700, John Stultz wrote:
> While enabling lockdep on seqlocks, I ran accross the warning below
> caused by the ipv6 stats being updated in both irq and non-irq context.
> 
> This is a novice attempt to correct the issue, and with this patch
> the warning goes away. Any better solutions would be appreciated!

...

>  
>  out_err_release:
> -	if (err == -ENETUNREACH)
> +	if (err == -ENETUNREACH) {
> +		unsigned long flags;
> +		/* some of the stats are locked in irq context */
> +		local_irq_save(flags);
>  		IP6_INC_STATS_BH(net, NULL, IPSTATS_MIB_OUTNOROUTES);
> +		local_irq_restore(flags);
> +	}
>  	dst_release(*dst);
>  	*dst = NULL;
>  	return err;

You better change IP6_INC_STATS_BH() to IP6_INC_STATS()

On x86 for example, no extra code will be generated (no need to disable
hard or soft irqs)



--
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/