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From: Michal Hocko <mhocko@kernel.org>
To: Yizhuo Zhai <yzhai003@ucr.edu>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	cgroups@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, Zhiyun Qian <zhiyunq@cs.ucr.edu>,
	Chengyu Song <csong@cs.ucr.edu>
Subject: Re: Potential NULL pointer deference in mm/memcontrol.c
Date: Thu, 10 Oct 2019 09:19:37 +0200	[thread overview]
Message-ID: <20191010071937.GA18412@dhcp22.suse.cz> (raw)
In-Reply-To: <CABvMjLRgShsBiod+GVcqirmKeFLN_KfxdDDwGo22YK0wULepwA@mail.gmail.com>

On Wed 09-10-19 21:56:04, Yizhuo Zhai wrote:
> Hi All:
> mm/memcontrol.c:
> The function mem_cgroup_from_css() could return NULL, but some callers

This is the case only when the memory cgroup controller is disabled
which is a boot time option.

> in this file
> checks the return value but directly dereference it, which seems
> potentially unsafe.
> Such callers include mem_cgroup_hierarchy_read(),
> mem_cgroup_hierarchy_write(), mem_cgroup_read_u64(),
> mem_cgroup_reset(), etc.

And none of those should be ever called under that condition AFAICS.

Thanks!
-- 
Michal Hocko
SUSE Labs


      reply	other threads:[~2019-10-10  7:33 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-10  4:56 Potential NULL pointer deference in mm/memcontrol.c Yizhuo Zhai
2019-10-10  7:19 ` Michal Hocko [this message]

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