netdev - Re: [PATCH v2 net] nfc: use GFP_USER for user-controlled kmalloc

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Message-ID: <1454096764.7627.66.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Fri, 29 Jan 2016 11:46:04 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Cong Wang <xiyou.wangcong@...il.com>
Cc:	netdev@...r.kernel.org, dvyukov@...gle.com,
	linux-wireless@...r.kernel.org, julian.calaby@...il.com,
	Lauro Ramos Venancio <lauro.venancio@...nbossa.org>,
	Aloisio Almeida Jr <aloisio.almeida@...nbossa.org>,
	Samuel Ortiz <sameo@...ux.intel.com>
Subject: Re: [PATCH v2 net] nfc: use GFP_USER for user-controlled kmalloc

On Fri, 2016-01-29 at 11:24 -0800, Cong Wang wrote:
> These two functions are called in sendmsg path, and the
> 'len' is passed from user-space, so we should not allow
> malicious users to OOM kernel on purpose.
> 
> Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: Lauro Ramos Venancio <lauro.venancio@...nbossa.org>
> Cc: Aloisio Almeida Jr <aloisio.almeida@...nbossa.org>
> Cc: Samuel Ortiz <sameo@...ux.intel.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
> ---

Note that the issue is not OOM the kernel (as the allocation is
attempted even after your patch), but having a way to
spill stack traces in the syslog.

Acked-by: Eric Dumazet <edumazet@...gle.com>

Thanks!