Re: [PATCH v2 1/2] KEYS: Don't write out to userspace while holding key semaphore

[Jarkko Sakkinen]

On Sun, Mar 08, 2020 at 01:04:09PM -0400, Waiman Long wrote:
> +		/*
> +		 * Read methods will just return the required length
> +		 * without any copying if the provided length isn't big
> +		 * enough.
> +		 */
> +		if ((ret > 0) && (ret <= buflen) && buffer &&
> +		    copy_to_user(buffer, tmpbuf, ret))
> +			ret = -EFAULT;

Please, reorg and remove redundant parentheses:

/*
 * Read methods will just return the required length
 * without any copying if the provided length isn't big
 * enough.
 */
if (ret > 0 && ret <= buflen) {
	if (buffer && copy_to_user(buffer, tmpbuf, ret))
		ret = -EFAULT;
}

Now the comment is attached to the exact right thing. The previous
organization is a pain to look at when backtracking commits for
whatever reason in the future.

I'm also wondering, would it be possible to rework the code in a way
that you don't have check whether buffer is valid on a constant basis?

/Jarkko