From: Andrew Morton <akpm@linux-foundation.org>
To: Will Deacon <will.deacon@arm.com>
Cc: Marc.Zyngier@arm.com, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, ericvh@gmail.com,
levinsasha928@gmail.com
Subject: Re: [PATCH v2 2/3] virtio: 9p: correctly pass physical address to userspace for high pages
Date: Mon, 22 Oct 2012 15:05:30 -0700 [thread overview]
Message-ID: <20121022150530.99caaecf.akpm@linux-foundation.org> (raw)
In-Reply-To: <1350651813-8694-2-git-send-email-will.deacon@arm.com>
On Fri, 19 Oct 2012 14:03:32 +0100
Will Deacon <will.deacon@arm.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?
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Will Deacon <will.deacon@arm.com>
Cc: linux-kernel@vger.kernel.org, rusty@rustcorp.com.au,
levinsasha928@gmail.com, Marc.Zyngier@arm.com,
virtualization@lists.linux-foundation.org, ericvh@gmail.com
Subject: Re: [PATCH v2 2/3] virtio: 9p: correctly pass physical address to userspace for high pages
Date: Mon, 22 Oct 2012 15:05:30 -0700 [thread overview]
Message-ID: <20121022150530.99caaecf.akpm@linux-foundation.org> (raw)
In-Reply-To: <1350651813-8694-2-git-send-email-will.deacon@arm.com>
On Fri, 19 Oct 2012 14:03:32 +0100
Will Deacon <will.deacon@arm.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?
next prev parent reply other threads:[~2012-10-22 22:05 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-19 13:03 [PATCH v2 1/3] mm: highmem: export kmap_to_page for modules Will Deacon
2012-10-19 13:03 ` Will Deacon
2012-10-19 13:03 ` [PATCH v2 2/3] virtio: 9p: correctly pass physical address to userspace for high pages Will Deacon
2012-10-19 13:03 ` Will Deacon
2012-10-22 22:05 ` Andrew Morton [this message]
2012-10-22 22:05 ` Andrew Morton
2012-10-19 13:03 ` [PATCH v2 3/3] virtio: force vring descriptors to be allocated from lowmem Will Deacon
2012-10-19 13:03 ` Will Deacon
2012-10-22 22:08 ` [PATCH v2 1/3] mm: highmem: export kmap_to_page for modules Andrew Morton
2012-10-22 22:08 ` Andrew Morton
2012-10-22 23:55 ` Rusty Russell
2012-10-22 23:55 ` Rusty Russell
2012-10-23 10:33 ` Will Deacon
2012-10-23 10:33 ` Will Deacon
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