From: Johannes Weiner <hannes@cmpxchg.org>
To: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>,
cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] memcg: Fix NULL pointer deref in task_in_mem_cgroup()
Date: Thu, 23 Oct 2014 14:19:29 -0400 [thread overview]
Message-ID: <20141023181929.GB15937@phnom.home.cmpxchg.org> (raw)
In-Reply-To: <1414082865-4091-1-git-send-email-jack@suse.cz>
On Thu, Oct 23, 2014 at 06:47:45PM +0200, Jan Kara wrote:
> 'curr' pointer in task_in_mem_cgroup() can be NULL when we race with
> somebody clearing task->mm. Check for it before dereferencing the
> pointer.
If task->mm is already NULL, we fall back to mem_cgroup_from_task(),
which definitely returns a memcg unless you pass NULL in there. So I
don't see how that could happen, and the NULL checks in the fallback
branch as well as in __mem_cgroup_same_or_subtree seem bogus to me.
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next prev parent reply other threads:[~2014-10-23 18:19 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-23 16:47 Jan Kara
2014-10-23 18:19 ` Johannes Weiner [this message]
2014-10-23 18:34 ` Jan Kara
2014-10-23 19:38 ` Johannes Weiner
2014-10-24 8:58 ` Michal Hocko
2014-10-24 13:36 ` Johannes Weiner
2014-10-24 13:42 ` Michal Hocko
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