linux-kernel - Re: [PATCH v2 1/4] md/raid10: fix null-ptr-deref of mreplace in raid10_sync

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Message-ID: <532a0a45-368b-2fee-6054-682c64bb12ce@huaweicloud.com>
Date:   Sat, 27 May 2023 09:29:52 +0800
From:   Li Nan <linan666@...weicloud.com>
To:     Yu Kuai <yukuai1@...weicloud.com>, linan666@...weicloud.com,
        song@...nel.org, bingjingc@...ology.com, allenpeng@...ology.com,
        alexwu@...ology.com, shli@...com, neilb@...e.de
Cc:     linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        yi.zhang@...wei.com, houtao1@...wei.com, yangerkun@...wei.com,
        "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH v2 1/4] md/raid10: fix null-ptr-deref of mreplace in
 raid10_sync_request



在 2023/5/27 9:21, Yu Kuai 写道:
> Hi,
> 
> 在 2023/05/26 15:45, linan666@...weicloud.com 写道:
>> From: Li Nan <linan122@...wei.com>
>>
>> need_replace will be set to 1 if no-Faulty mreplace exists, and mreplace
>> will be deref later. However, the latter check of mreplace might set
>> mreplace to NULL, null-ptr-deref occurs if need_replace is 1 at this 
>> time.
>>
>> Fix it by merging two checks into one. And replace 'need_replace' with
>> 'mreplace' because their values are always the same.
>>
>> Fixes: ee37d7314a32 ("md/raid10: Fix raid10 replace hang when new 
>> added disk faulty")
>> Signed-off-by: Li Nan <linan122@...wei.com>
> 
> Other than some nits below, this patch looks good to me, feel free too
> add:
> 
> Reviewed-by: Yu Kuai <yukuai3@...wei.com>
>> ---
>>   drivers/md/raid10.c | 13 +++++--------
>>   1 file changed, 5 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
>> index 4fcfcb350d2b..e21502c03b45 100644
>> --- a/drivers/md/raid10.c
>> +++ b/drivers/md/raid10.c
>> @@ -3438,7 +3438,6 @@ static sector_t raid10_sync_request(struct mddev 
>> *mddev, sector_t sector_nr,
>>               int must_sync;
>>               int any_working;
>>               int need_recover = 0;
>> -            int need_replace = 0;
>>               struct raid10_info *mirror = &conf->mirrors[i];
>>               struct md_rdev *mrdev, *mreplace;
>> @@ -3451,10 +3450,10 @@ static sector_t raid10_sync_request(struct 
>> mddev *mddev, sector_t sector_nr,
>>                   !test_bit(In_sync, &mrdev->flags))
>>                   need_recover = 1;
>>               if (mreplace != NULL &&
>> -                !test_bit(Faulty, &mreplace->flags))
>> -                need_replace = 1;
>> +                test_bit(Faulty, &mreplace->flags))
> This can be keeped in one line.
> 

OK, I will change it.
Thanks for your review.

-- 
Thanks,
Nan