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From: Muchun Song <songmuchun@bytedance.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Andi Kleen <ak@linux.intel.com>,
	Linux Memory Management List <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [External] Re: [PATCH] mm/hugetlb: Fix a race between hugetlb sysctl handlers
Date: Fri, 28 Aug 2020 10:33:40 +0800	[thread overview]
Message-ID: <CAMZfGtU9U5dv5oOCopnsFN7XErY52nA47b0jreUqZ2C6VBmC7w@mail.gmail.com> (raw)
In-Reply-To: <afaa721e-f86c-9b49-acd1-54c9017fb269@oracle.com>

On Fri, Aug 28, 2020 at 5:51 AM Mike Kravetz <mike.kravetz@oracle.com> wrote:
>
> On 8/25/20 7:47 PM, Muchun Song wrote:
> >
> > CPU0:                                     CPU1:
> >                                           proc_sys_write
> > hugetlb_sysctl_handler                      proc_sys_call_handler
> > hugetlb_sysctl_handler_common                 hugetlb_sysctl_handler
> >   table->data = &tmp;                           hugetlb_sysctl_handler_common
> >                                                   table->data = &tmp;
> >     proc_doulongvec_minmax
> >       do_proc_doulongvec_minmax             sysctl_head_finish
> >         __do_proc_doulongvec_minmax
> >           i = table->data;
> >           *i = val;     // corrupt CPU1 stack
>
> Thanks Muchun!
> Can you please add this to the commit message.

OK, I will do that. Thanks.

>
> Also, when looking closer at the patch I do not think setting table->maxlen
> is necessary in these routines.  maxlen is set when the hugetlb ctl_table
> entries are defined and initialized.  This is not something you introduced.
> The unnecessary assignments are in the existing code.  However, there is no
> need to carry them forward.

Yeah, I agree with you. I will remove the unnecessary assignment of
table->maxlen.

>
> --
> Mike Kravetz



-- 
Yours,
Muchun

  reply	other threads:[~2020-08-28  2:34 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-22  9:53 [PATCH] mm/hugetlb: Fix a race between hugetlb sysctl handlers Muchun Song
2020-08-24 20:59 ` Andrew Morton
2020-08-24 21:19   ` Mike Kravetz
2020-08-25  3:01     ` [External] " Muchun Song
2020-08-26  0:01       ` Mike Kravetz
2020-08-26  2:47         ` Muchun Song
2020-08-27 21:51           ` Mike Kravetz
2020-08-28  2:33             ` Muchun Song [this message]
2020-08-25  2:42 ` Muchun Song
2020-08-25 15:25 ` Andi Kleen
2020-08-26  2:34   ` [Phishing Risk] [External] " Muchun Song

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