linux-kernel - Re: [PATCH] fanotify_user: use upper_32

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Date:   Thu, 25 Mar 2021 15:34:28 +0100
From:   Jan Kara <jack@...e.cz>
To:     Christian Brauner <brauner@...nel.org>
Cc:     Jan Kara <jack@...e.cz>, Amir Goldstein <amir73il@...il.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Christian Brauner <christian.brauner@...ntu.com>
Subject: Re: [PATCH] fanotify_user: use upper_32_bits() to verify mask

On Thu 25-03-21 09:37:43, Christian Brauner wrote:
> From: Christian Brauner <christian.brauner@...ntu.com>
> 
> I don't see an obvious reason why the upper 32 bit check needs to be
> open-coded this way. Switch to upper_32_bits() which is more idiomatic and
> should conceptually be the same check.
> 
> Cc: Amir Goldstein <amir73il@...il.com>
> Cc: Jan Kara <jack@...e.cz>
> Signed-off-by: Christian Brauner <christian.brauner@...ntu.com>

Thanks for the cleanup. I've added it to my tree.

								Honza

> ---
>  fs/notify/fanotify/fanotify_user.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 9e0c1afac8bd..d5683fa9d495 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -1126,7 +1126,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
>  		 __func__, fanotify_fd, flags, dfd, pathname, mask);
>  
>  	/* we only use the lower 32 bits as of right now. */
> -	if (mask & ((__u64)0xffffffff << 32))
> +	if (upper_32_bits(mask))
>  		return -EINVAL;
>  
>  	if (flags & ~FANOTIFY_MARK_FLAGS)
> 
> base-commit: 0d02ec6b3136c73c09e7859f0d0e4e2c4c07b49b
> -- 
> 2.27.0
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR