[PATCH] hyperv: mshv: zero VTL hypercall input page

[Yousef Alhouseen]

mshv_vtl_hvcall_call() copies only the user-provided input size.

It then passes the page to hv_do_hypercall().

For short inputs, stale bytes can remain in the bounce page.

Those bytes can be consumed by the hypervisor.

Allocate the input page zeroed, matching the output page.

Signed-off-by: Yousef Alhouseen <alhouseenyousef@xxxxxxxxx>
---
 drivers/hv/mshv_vtl_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
index 0365d207c..f2633148c 100644
--- a/drivers/hv/mshv_vtl_main.c
+++ b/drivers/hv/mshv_vtl_main.c
@@ -1146,7 +1146,7 @@ static int mshv_vtl_hvcall_call(struct mshv_vtl_hvcall_fd *fd,
 	 *
 	 * TODO: Take care of this when CVM support is added.
 	 */
-	in = (void *)__get_free_page(GFP_KERNEL);
+	in = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
 	out = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
 	if (!in || !out) {
 		ret = -ENOMEM;
-- 
2.54.0