3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Will Deacon <will.dea...@arm.com>

commit 30d395b124c51db66d9f3ba0611cd62021afc392 upstream.

commit b9cdc88df8e63e81c723b82c286fc97f5d0dc325 upstream.

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: Sasha Levin <levinsasha...@gmail.com>
Signed-off-by: Will Deacon <will.dea...@arm.com>
Signed-off-by: Rusty Russell <ru...@rustcorp.com.au>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
Cc: Yijing Wang <wangyij...@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 net/9p/trans_virtio.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- 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 vi
                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--;
                }


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