Re: [PATCH] fs/proc/kcore: reinstate bounce buffer for KCORE_TEXT regions

[David Hildenbrand]

> > > Hm good point, actually, now we're using the bounce buffer we don't need to
> > > avoid usermode hardening any more.
> > >
> > > However since we've established a bounce buffer ourselves its still
> > > appropriate to use _copy_to_iter() as we know the source region is good to
> > > copy from.
> > >
> > > To make life easy I'll just respin with an updated comment :)
> >
> > I'm not too picky this time, no need to resend if everybody else is fine :P
>
> Haha you know the classic Lorenzo respin spiral and want to avoid it I see ;)

Don't want to make your apparently stressful week more stressful. Not 
this time ;)

> The comment is actually inaccurate now, so to avoid noise + make life easy
> (maybe) for Andrew here's a fix patch that just corrects the comment:-
>
> ----8<----
>
>  From d2b8fb271f21b79048e5630699133f77a93d0481 Mon Sep 17 00:00:00 2001
> From: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
> Date: Tue, 1 Aug 2023 17:36:08 +0100
> Subject: [PATCH] fs/proc/kcore: correct comment
>
> Correct comment to be strictly correct about reasoning.
>
> Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
> ---
>   fs/proc/kcore.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
> index 3bc689038232..23fc24d16b31 100644
> --- a/fs/proc/kcore.c
> +++ b/fs/proc/kcore.c
> @@ -568,8 +568,8 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter)
>   					goto out;
>   				}
>   			/*
> -			 * We use _copy_to_iter() to bypass usermode hardening
> -			 * which would otherwise prevent this operation.
> +			 * We know the bounce buffer is safe to copy from, so
> +			 * use _copy_to_iter() directly.
>   			 */
>   			} else if (_copy_to_iter(buf, tsz, iter) != tsz) {
>   				ret = -EFAULT;
> --
> 2.41.0

Thanks!

Acked-by: David Hildenbrand <david@xxxxxxxxxx>

--
Cheers,

David / dhildenb