linux-kernel - rcu_do_batch: rcu_data->qlen is not irq safe

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-next>] [day] [month] [year] [list]

Message-ID: <20060910150820.GA7433@oleg>
Date:	Sun, 10 Sep 2006 19:08:20 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	"Paul E. McKenney" <paulmck@...ibm.com>,
	Dipankar Sarma <dipankar@...ibm.com>,
	Srivatsa Vaddagiri <vatsa@...ibm.com>,
	Andrew Morton <akpm@...l.org>
Cc:	linux-kernel@...r.kernel.org
Subject: rcu_do_batch: rcu_data->qlen is not irq safe

rcu_do_batch() decrements rdp->qlen with irqs enabled.
This is not good, it can also be modified by call_rcu()
from interrupt.

So, is it worth fixing? The problem is mostly theoretical.

If yes, is it ok to use local_t ? Iirc, the were some
problems with local_t on some arches. Sometimes it is
just atomic_t ...

Otherwise, we can update ->qlen after the main loop,

	local_irq_disable();
	rdp->qlen -= count;
	local_irq_enable();

What dou you think?

Oleg.

-
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/