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Subject: Re: [PATCH v2] xfrm: policy: Fix doulbe free in xfrm_policy_timer
To:     Herbert Xu <herbert@gondor.apana.org.au>
References: <20200318034839.57996-1-yuehaibing@huawei.com>
 <20200323014155.56376-1-yuehaibing@huawei.com>
 <20200323062914.GA5811@gondor.apana.org.au>
CC:     <steffen.klassert@secunet.com>, <davem@davemloft.net>,
        <kuba@kernel.org>, <timo.teras@iki.fi>, <netdev@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
From:   Yuehaibing <yuehaibing@huawei.com>
Message-ID: <52f2d9b2-e66a-f2aa-52fb-d0a3ca748a73@huawei.com>
Date:   Mon, 23 Mar 2020 15:04:01 +0800
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On 2020/3/23 14:29, Herbert Xu wrote:
> On Mon, Mar 23, 2020 at 09:41:55AM +0800, YueHaibing wrote:
>>
>> diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
>> index dbda08ec566e..ae0689174bbf 100644
>> --- a/net/xfrm/xfrm_policy.c
>> +++ b/net/xfrm/xfrm_policy.c
>> @@ -434,6 +434,7 @@ EXPORT_SYMBOL(xfrm_policy_destroy);
>>  
>>  static void xfrm_policy_kill(struct xfrm_policy *policy)
>>  {
>> +	write_lock_bh(&policy->lock);
>>  	policy->walk.dead = 1;
>>  
>>  	atomic_inc(&policy->genid);
>> @@ -445,6 +446,7 @@ static void xfrm_policy_kill(struct xfrm_policy *policy)
>>  	if (del_timer(&policy->timer))
>>  		xfrm_pol_put(policy);
>>  
>> +	write_unlock_bh(&policy->lock);
> 
> Why did you expand the critical section? Can't you just undo the
> patch in xfrm_policy_kill?

Indeed, the critical section should not be expanded, thanks!

> 
> Cheers,
>