[PATCH 4.9 63/63] drivers: hv: Turn off write permission on the hypercall page

[Greg Kroah-Hartman]

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

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

From: K. Y. Srinivasan <k...@microsoft.com>

commit 372b1e91343e657a7cc5e2e2bcecd5140ac28119 upstream.

The hypercall page only needs to be executable but currently it is setup to
be writable as well. Fix the issue.

Signed-off-by: K. Y. Srinivasan <k...@microsoft.com>
Acked-by: Kees Cook <keesc...@chromium.org>
Reported-by: Stephen Hemminger <step...@networkplumber.org>
Tested-by: Stephen Hemminger <step...@networkplumber.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/hv/hv.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -220,7 +220,7 @@ int hv_init(void)
        /* See if the hypercall page is already set */
        rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 
-       virtaddr = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_EXEC);
+       virtaddr = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
 
        if (!virtaddr)
                goto cleanup;