linux-kernel - Re: [PATCH 1/2] random: convert to using fops->read

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Message-ID: <YodcCV96t13O0Trl@zx2c4.com>
Date:   Fri, 20 May 2022 11:14:49 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Jens Axboe <axboe@...nel.dk>, tytso@....edu, hch@....de,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] random: convert to using fops->read_iter()

Hi Al,

On Fri, May 20, 2022 at 03:11:06AM +0000, Al Viro wrote:
> >  SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len,
> >  unsigned int, flags) { +	struct iovec iov = { .iov_base = ubuf };
> >  +	struct iov_iter iter;
> 
> 	import_single_range(READ, ubuf, len, &iov, &iter)
> 
> (note, BTW, that this'll cap len)

I'll incorporate this and send a v4. import_single_range does an
access_ok(), but I would hope that copy_to_iter() also does similar
checks. Does that make this less efficient?

Jason