linux-kernel - Re: [RFC PATCH] sysrq: don't hold the sysrq_key_table

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] [day] [month] [year] [list]

Date:	Tue, 27 Jul 2010 16:36:22 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Xiaotian Feng <dfeng@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Neil Horman <nhorman@...driver.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [RFC PATCH] sysrq: don't hold the sysrq_key_table_lock during
 the handler

On Mon, 26 Jul 2010 17:54:02 +0800
Xiaotian Feng <dfeng@...hat.com> wrote:

> sysrq_key_table_lock is used to protect the sysrq_key_table, make sure
> we get/replace the right operation for the sysrq. But in __handle_sysrq,
> kernel will hold this lock and disable irqs until we finished op_p->handler().
> This may cause false positive watchdog alert when we're doing "show-task-states"
> on a system with many tasks.
> 

It would be better to find a suitable point in an inner loop and add an
appropriately-commented touch_nmi_watchdog().

That way the problem gets fixed for all irqs-off callers, not just one
of them.

--
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/