Messages in this thread | | | Date | Mon, 22 Oct 2012 15:05:30 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH v2 2/3] virtio: 9p: correctly pass physical address to userspace for high pages |
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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?
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