From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cong Wang <amwang@redhat.com>
Subject: Re: [Patch V2] proc: check error pointer returned by m_start()
Date: Mon, 28 Mar 2011 13:49:09 +0800
Message-ID: <4D902155.8040602@redhat.com>
References: <AANLkTi=mqKF=xeMYbj9LZgPfSLHSkO1JRXsNTW3LyHqu@mail.gmail.com>	<1301289993-24248-1-git-send-email-amwang@redhat.com> <AANLkTik32QRUMaKF1aZ02Crh+RFG_4VOCFgPUPnCNLZA@mail.gmail.com>
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Cc: linux-kernel@vger.kernel.org, WANG Cong <xiyou.wangcong@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Eric B Munson <emunson@mgebm.net>,
	David Rientjes <rientjes@google.com>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	Mel Gorman <mel@csn.ul.ie>, linux-fsdevel@vger.kernel.org
To: Anca Emanuel <anca.emanuel@gmail.com>
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In-Reply-To: <AANLkTik32QRUMaKF1aZ02Crh+RFG_4VOCFgPUPnCNLZA@mail.gmail.com>
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=E4=BA=8E 2011=E5=B9=B403=E6=9C=8828=E6=97=A5 13:46, Anca Emanuel =E5=86=
=99=E9=81=93:
> On Mon, Mar 28, 2011 at 8:26 AM, Amerigo Wang<amwang@redhat.com>  wro=
te:
>> From: WANG Cong<xiyou.wangcong@gmail.com>
>>
>> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
>> index 7c708a4..8e59169 100644
>> --- a/fs/proc/task_mmu.c
>> +++ b/fs/proc/task_mmu.c
>> @@ -124,8 +124,10 @@ static void *m_start(struct seq_file *m, loff_t=
 *pos)
>>                 return ERR_PTR(-ESRCH);
>>
>>         mm =3D mm_for_maps(priv->task);
>> -       if (!mm || IS_ERR(mm))
>> +       if (IS_ERR_OR_NULL(mm)) {
>> +               put_task_struct(priv->task);
>>                 return mm;
>> +       }
>>         down_read(&mm->mmap_sem);
>>
>>         tail_vma =3D get_gate_vma(priv->task->mm);
>> @@ -182,6 +184,8 @@ static void m_stop(struct seq_file *m, void *v)
>>         struct proc_maps_private *priv =3D m->private;
>>         struct vm_area_struct *vma =3D v;
>>
>> +       if (IS_ERR_OR_NULL(v))
>> +               return;
>
> Note: this is not functional equivalent with the previous patch.
>

I moved that put_task_struct() into m_start() itself.

>
> I din't test the above patch.
>
> Linus already have the fix in his tree.

Yes, I really should pull before I made a patch. :-/

Anyway, thanks for reporting and testing.