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virtio: 9p: correctly pass physical address to userspace for high pages 

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.

Cc: stable@kernel.org
Cc: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Will Deacon 2012-10-19 14:03:32 +01:00 committed by Rusty Russell
parent f0263d2d22
commit b9cdc88df8
1 changed files with 2 additions and 1 deletions
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3
net/9p/trans_virtio.c
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@ -39,6 +39,7 @@
#include <linux/inet.h> #include <linux/inet.h>
#include <linux/idr.h> #include <linux/idr.h>
#include <linux/file.h> #include <linux/file.h>
#include <linux/highmem.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <net/9p/9p.h> #include <net/9p/9p.h>
#include <linux/parser.h> #include <linux/parser.h>
@ -325,7 +326,7 @@ static int p9_get_mapped_pages(struct virtio_chan *chan,
int count = nr_pages; int count = nr_pages;
while (nr_pages) { while (nr_pages) {
s = rest_of_page(data); s = rest_of_page(data);
pages[index++] = virt_to_page(data); pages[index++] = kmap_to_page(data);
data += s; data += s;
nr_pages--; nr_pages--;
} }