linux-kernel - Re: [PATCH] uio: fix is_source param for check_copy_size() in copy_to_iter

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Message-ID: <c81d5d9d-4d9f-917f-d7f5-4d9a4dc6e146@intel.com>
Date:   Thu, 6 Sep 2018 08:45:58 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     gregkh@...uxfoundation.org
Cc:     dan.j.williams@...el.com, vishal.l.verma@...el.com,
        fan.du@...el.com, linux-nvdimm@...ts.01.org,
        linux-kernel@...r.kernel.org,
        Wenwei Tao <wenwei.tww@...baba-inc.com>
Subject: Re: [PATCH] uio: fix is_source param for check_copy_size() in
 copy_to_iter_mcsafe()



On 09/05/2018 01:31 PM, Dave Jiang wrote:
> copy_to_iter_mcsafe() is passing in the is_source parameter as "false"
> to check_copy_size(). This is different than what copy_to_iter() does.
> Also, the addr parameter passed to check_copy_size() is the source so
> therefore we should be passing in "true" instead.
> 
> Fixes: 8780356ef630 ("x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()")
> 
> Reported-by: Fan Du <fan.du@...el.com>
Slight correction:
Reported-by: Wenwei Tao <wenwei.tww@...baba-inc.com>

> Signed-off-by: Dave Jiang <dave.jiang@...el.com>
> Reviewed-by: Vishal Verma <vishal.l.verma@...el.com>
> ---
>  include/linux/uio.h |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/uio.h b/include/linux/uio.h
> index 409c845d4cd3..422b1c01ee0d 100644
> --- a/include/linux/uio.h
> +++ b/include/linux/uio.h
> @@ -172,7 +172,7 @@ size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
>  static __always_inline __must_check
>  size_t copy_to_iter_mcsafe(void *addr, size_t bytes, struct iov_iter *i)
>  {
> -	if (unlikely(!check_copy_size(addr, bytes, false)))
> +	if (unlikely(!check_copy_size(addr, bytes, true)))
>  		return 0;
>  	else
>  		return _copy_to_iter_mcsafe(addr, bytes, i);
>