Re: [PATCH RESEND 3/3] lib: Fix length calculation in extract_kvec_to_sg

[Andrew Morton]

On Mon, 23 Mar 2026 22:23:50 +0100 "Christian A. Ehrhardt" <lk@xxxxxxx> wrote:

> When extracting from a kvec to a scatterlist, do not
> cross page boundaries. The required length is already
> calculated but not used as intended.
> 
> The previous changes to the kunit_iov_iter.c demonstrate
> that the patch is necessary.

Thanks.

> Cc: David Howells <dhowells@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # v6.5+

Could we please have a description of the userspace-visible impact?  To
help others understand why we're proposing a backport,

> --- a/lib/scatterlist.c
> +++ b/lib/scatterlist.c
> @@ -1249,7 +1249,7 @@ static ssize_t extract_kvec_to_sg(struct iov_iter *iter,
>  			else
>  				page = virt_to_page((void *)kaddr);
>  
> -			sg_set_page(sg, page, len, off);
> +			sg_set_page(sg, page, seg, off);
>  			sgtable->nents++;
>  			sg++;
>  			sg_max--;

I'm thinking the series should be split up - this patch for 7.0-rcX and
-stable, the kunit changes for 7.0-rcX.  Or do you think we should
-stableize the kunit changes also?

Or we put it all into 7.0-rcX and let the -stable patch trickle back
later on.  After all, 018584697533 was a couple of years ago.  It's hard
to decide on these things without that userspace-visible impact thing!