Re: [PATCH 5.19 089/101] dont use __kernel_write() on kmap_local_page()

[Greg Kroah-Hartman]

On Mon, Oct 03, 2022 at 11:09:12AM +0200, Geert Uytterhoeven wrote:
> Hi Greg,
> 
> On Mon, Oct 3, 2022 at 9:28 AM Greg Kroah-Hartman
> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> > From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> >
> > [ Upstream commit 06bbaa6dc53cb72040db952053432541acb9adc7 ]
> >
> > passing kmap_local_page() result to __kernel_write() is unsafe -
> > random ->write_iter() might (and 9p one does) get unhappy when
> > passed ITER_KVEC with pointer that came from kmap_local_page().
> >
> > Fix by providing a variant of __kernel_write() that takes an iov_iter
> > from caller (__kernel_write() becomes a trivial wrapper) and adding
> > dump_emit_page() that parallels dump_emit(), except that instead of
> > __kernel_write() it uses __kernel_write_iter() with ITER_BVEC source.
> >
> > Fixes: 3159ed57792b "fs/coredump: use kmap_local_page()"
> > Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> 
> This will need a follow-up patch, which I have just posted[1], to
> not break the build if CONFIG_ELF_CORE is not set.
> 
> [1] https://lore.kernel.org/20221003090657.2053236-1-geert@xxxxxxxxxxxxxx

Thanks, now dropped from 5.19 and 5.15 queues.  When this gets merged,
can you ping stable@xxxxxxxxxx to add them both back?

thanks,

greg k-h