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Subject: Re: [PATCH v2] md: raid1: fix potential OOB in raid1_remove_disk()
To:     Zhang Shurong <zhang_shurong@foxmail.com>, song@kernel.org,
        yukuai1@huaweicloud.com
Cc:     linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org,
        "yukuai (C)" <yukuai3@huawei.com>
References: <tencent_0D24426FAC6A21B69AC0C03CE4143A508F09@qq.com>
From:   Yu Kuai <yukuai1@huaweicloud.com>
Message-ID: <d8fde5d9-3ac5-0945-dc8e-315092a67528@huaweicloud.com>
Date:   Mon, 24 Jul 2023 10:11:46 +0800
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?? 2023/07/22 15:53, Zhang Shurong д??:
> If rddev->raid_disk is greater than mddev->raid_disks, there will be
> an out-of-bounds in raid1_remove_disk(). We have already found
> similar reports as follows:
> 
> 1) commit d17f744e883b ("md-raid10: fix KASAN warning")
> 2) commit 1ebc2cec0b7d ("dm raid: fix KASAN warning in raid5_remove_disk")
> 
> Fix this bug by checking whether the "number" variable is
> valid.

LGTM

Reviewed-by: Yu Kuai <yukuai3@huawei.com>
> 
> Signed-off-by: Zhang Shurong <zhang_shurong@foxmail.com>
> ---
> Changes in v2:
>   - Using conf->raid_disks instead of mddev->raid_disks.
> 
>   drivers/md/raid1.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index dd25832eb045..80aeee63dfb7 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -1829,6 +1829,10 @@ static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
>   	struct r1conf *conf = mddev->private;
>   	int err = 0;
>   	int number = rdev->raid_disk;
> +
> +	if (unlikely(number >= conf->raid_disks))
> +		goto abort;
> +
>   	struct raid1_info *p = conf->mirrors + number;
>   
>   	if (rdev != p->rdev)
>