linux-kernel - Re: [PATCH 5/5] tracing: Do not record user stack trace from NMI context

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]

Message-ID: <20100317020759.GE5258@nowhere>
Date:	Wed, 17 Mar 2010 03:08:01 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Li Zefan <lizf@...fujitsu.com>,
	Lai Jiangshan <laijs@...fujitsu.com>, stable@...nel.org
Subject: Re: [PATCH 5/5] tracing: Do not record user stack trace from NMI
	context

On Sun, Mar 14, 2010 at 12:58:40PM -0400, Steven Rostedt wrote:
> On Sun, 2010-03-14 at 11:27 +0100, Frederic Weisbecker wrote:
> 
> > 
> > Wow, that's a race :)
> > 
> > In perf this is dealt with a special copy_from_user_nmi()
> > (see in arch/x86/kernel/cpu/perf_event.c)
> > 
> > May be save_stack_trace_user() should use that instead
> > of a __copy_from_user_inatomic() based thing, just to
> > cover such NMI corner race case.
> > 
> 
> Yeah, we should move the __copy_from_user_nmi() out of the perf code and
> into the normal uaccess code. Then we could do as you suggest, and have
> the stack code do:
> 
> if (in_nmi())
> 	__copy_from_user_nmi();
> else
> 	__copy_from_user_inatomic();
> 
> Or maybe it would be best to have the __copy_from_user_inatomic() handle
> it.


Yeah, agreed.

--
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/