From: Michal Hocko <mhocko@suse.com>
To: Jiang Biao <benbjiang@gmail.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, robinlai@tencent.com,
benbjiang@tencent.com
Subject: Re: [PATCH] mm/oom_kill: fix wild pointer in out_of_memory
Date: Mon, 15 Mar 2021 09:22:07 +0100 [thread overview]
Message-ID: <YE8ZL8VTllD5RLOf@dhcp22.suse.cz> (raw)
In-Reply-To: <20210313042300.3833-1-benbjiang@gmail.com>
On Sat 13-03-21 12:23:00, Jiang Biao wrote:
> From: Bin Lai <robinlai@tencent.com>
>
> From: Bin Lai <robinlai@tencent.com>
>
> The oc->chosen is used by oom implementation, and the caller does
> not initialize this variable. If the tasks of memcg are all unkillable,
> oom_evaluate_task cann't choose any task, and the oc->chosen will be
> a wild pointer. So we should initialize oc->chosen before calling
> oom_evaluate_task.
All callers do initialize oom_control on the stack and even partial
structure initialization on stack will result in the zeroying of all
other structure's element. So I do not think there is any problem.
>
> Signed-off-by: Bin Lai <robinlai@tencent.com>
> Reviewed-by: Jiang Biao <benbjiang@tencent.com>
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 9efaf43..0658a30 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -366,6 +366,7 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
> static void select_bad_process(struct oom_control *oc)
> {
> oc->chosen_points = LONG_MIN;
> + oc->chosen = NULL;
>
> if (is_memcg_oom(oc))
> mem_cgroup_scan_tasks(oc->memcg, oom_evaluate_task, oc);
> --
> 1.8.3.1
>
--
Michal Hocko
SUSE Labs
prev parent reply other threads:[~2021-03-15 8:22 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-13 4:23 [PATCH] mm/oom_kill: fix wild pointer in out_of_memory Jiang Biao
2021-03-15 8:22 ` Michal Hocko [this message]
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