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Message-ID: <225f4c8e-0e2c-8f4b-f87d-69f4677af572@huaweicloud.com>
Date: Mon, 3 Jun 2024 10:19:50 +0800
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Subject: Re: [PATCH] ublk_drv: fix NULL pointer dereference in
 ublk_ctrl_start_recovery()
To: Ming Lei <ming.lei@redhat.com>
Cc: axboe@kernel.dk, ZiyangZhang@linux.alibaba.com, czhong@redhat.com,
 linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
 yukuai3@huawei.com, yi.zhang@huawei.com, houtao1@huawei.com,
 yangerkun@huawei.com
References: <20240529095313.2568595-1-linan666@huaweicloud.com>
 <Zl0QpCbYVHIkKa/H@fedora>
From: Li Nan <linan666@huaweicloud.com>
In-Reply-To: <Zl0QpCbYVHIkKa/H@fedora>
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在 2024/6/3 8:39, Ming Lei 写道:

[...]

>> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
>> index 4e159948c912..99b621b2d40f 100644
>> --- a/drivers/block/ublk_drv.c
>> +++ b/drivers/block/ublk_drv.c
>> @@ -2630,7 +2630,8 @@ static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)
>>   {
>>   	int i;
>>   
>> -	WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq)));
>> +	if (WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq))))
>> +		return;
> 
> Yeah, it is one bug. However, it could be addressed by adding the check in
> ublk_ctrl_start_recovery() and return immediately in case of NULL ubq->ubq_daemon,
> what do you think about this way?
> 

Check ub->nr_queues_ready seems better. How about:

@@ -2662,6 +2662,8 @@ static int ublk_ctrl_start_recovery(struct 
ublk_device *ub,
         mutex_lock(&ub->mutex);
         if (!ublk_can_use_recovery(ub))
                 goto out_unlock;
+       if (!ub->nr_queues_ready)
+               goto out_unlock;
         /*
          * START_RECOVERY is only allowd after:
          *

> 
> Thanks,
> Ming

-- 
Thanks,
Nan