linux-kernel - Re: [PATCH] tty: serial: msm: Fix lock init issue with earlycon

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, 21 Oct 2014 15:42:00 -0400
From:	Peter Hurley <peter@...leysoftware.com>
To:	Stephen Boyd <sboyd@...eaurora.org>
CC:	Kumar Gala <galak@...eaurora.org>, gregkh@...uxfoundation.org,
	linux-kernel@...r.kernel.org,
	linux-arm-msm <linux-arm-msm@...r.kernel.org>,
	linux-arm-kernel@...ts.infradead.org, Rob Herring <robh@...nel.org>
Subject: Re: [PATCH] tty: serial: msm: Fix lock init issue with earlycon

On 10/20/2014 06:20 PM, Stephen Boyd wrote:
> On 10/20, Stephen Boyd wrote:
>> On 10/20, Peter Hurley wrote:
>>>
>>> FWIW, __msm_console_write() is a deadlock-waiting-to_happen since it does
>>> not disable interrupts with spin_lock_irqsave().
>>>
>>
>> Yeah we should fix that. As far as I can tell we've never used
>> the irqsave variant of the lock in the console path. Did this
>> become necessary at some point since this driver was introduced?
>> I'm wondering how many stable trees need the fix.
> 
> Actually I don't see this case. It looks like the console is
> always called in call_console_drivers() with irqs saved and
> disabled via the logbuf_lock in console_cont_flush() or
> console_unlock().

Thanks for bringing that to my attention.

That looks like a vestige of the initial transition away from BKL.
I might look into just disabling preemption; even that might not
really be necessary.

Regards,
Peter Hurley

--
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/