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

From: Greg Kroah-Hartman
Date: Mon Mar 13 2017 - 04:45:25 EST

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


From: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>

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 <kys@xxxxxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reported-by: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
Tested-by: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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;