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Date:   Wed, 8 Jan 2020 05:31:53 -0800
From:   Christoph Hellwig <hch@infradead.org>
To:     Zhiqiang Liu <liuzhiqiang26@huawei.com>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        jens.axboe@oracle.com, namhyung@gmail.com, bharrosh@panasas.com,
        renxudong <renxudong1@huawei.com>,
        Mingfangsen <mingfangsen@huawei.com>, zhengbin13@huawei.com,
        Guiyao <guiyao@huawei.com>
Subject: Re: [PATCH] blk-map: add kernel address validation in
 blk_rq_map_kern func
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On Mon, Dec 30, 2019 at 08:17:41PM +0800, Zhiqiang Liu wrote:
> +	if (!len || !virt_addr_valid(kbuf))

While this is a somewhat useful sanity check, it should never triggger
except for a grave bug in the caller.  So this needs a WARN_ON_ONCE
and a better explanation on how you triggered it, and most likely a
real fix for the caller.