Re: [PATCH] blk-map: add kernel address validation in blk_rq_map_kern func

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

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.