linux-kernel - Re: [PATCH v2 2/3] virtio: 9p: correctly pass physical address to userspace for high pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 22 Oct 2012 15:05:30 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Will Deacon <will.deacon@....com>
Cc:	linux-kernel@...r.kernel.org, rusty@...tcorp.com.au,
	levinsasha928@...il.com, Marc.Zyngier@....com,
	virtualization@...ts.linux-foundation.org, ericvh@...il.com
Subject: Re: [PATCH v2 2/3] virtio: 9p: correctly pass physical address to
 userspace for high pages

On Fri, 19 Oct 2012 14:03:32 +0100
Will Deacon <will.deacon@....com> wrote:

> When using a virtio transport, the 9p net device may pass the physical
> address of a kernel buffer to userspace via a scatterlist inside a
> virtqueue. If the kernel buffer is mapped outside of the linear mapping
> (e.g. highmem), then virt_to_page will return a bogus value and we will
> populate the scatterlist with junk.
> 
> This patch uses kmap_to_page when populating the page array for a kernel
> buffer.
> 
> ...
>
> --- a/net/9p/trans_virtio.c
> +++ b/net/9p/trans_virtio.c
> @@ -39,6 +39,7 @@
>  #include <linux/inet.h>
>  #include <linux/idr.h>
>  #include <linux/file.h>
> +#include <linux/highmem.h>
>  #include <linux/slab.h>
>  #include <net/9p/9p.h>
>  #include <linux/parser.h>
> @@ -325,7 +326,7 @@ static int p9_get_mapped_pages(struct virtio_chan *chan,
>  		int count = nr_pages;
>  		while (nr_pages) {
>  			s = rest_of_page(data);
> -			pages[index++] = virt_to_page(data);
> +			pages[index++] = kmap_to_page(data);
>  			data += s;
>  			nr_pages--;

I am suspecting that this code has been busted for a while on x86
highmem, but nobody noticed.  True or false?  If "true" then I expect
that a -stable backport is appropriate?

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/