linux-kernel - Re: [PATCH v2] xfrm: policy: Fix doulbe free in xfrm_policy

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Date:   Mon, 23 Mar 2020 15:04:01 +0800
From:   Yuehaibing <yuehaibing@...wei.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
CC:     <steffen.klassert@...unet.com>, <davem@...emloft.net>,
        <kuba@...nel.org>, <timo.teras@....fi>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] xfrm: policy: Fix doulbe free in xfrm_policy_timer

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,
>