From: Will Deacon <will.deacon@arm.com>
Date: Fri, 19 Oct 2012 13:03:32 +0000 (+0100)
Subject: virtio: 9p: correctly pass physical address to userspace for high pages
X-Git-Tag: v3.4.93~30
X-Git-Url: https://git.fsl.cs.sunysb.edu/?a=commitdiff_plain;h=6330a0c429c1518714283be51b86dc02b45db882;p=unionfs-2.6.39.y.git

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

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 <levinsasha928@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index 052d343d43f..9f4fcc5419e 100644
--- 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--;
 		}