linux-kernel - [PATCH 3.16 116/212] drivers: hv: Turn off write permission on the hypercall page

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Date:   Thu, 01 Jun 2017 16:43:16 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Kees Cook" <keescook@...omium.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        "Stephen Hemminger" <stephen@...workplumber.org>
Subject: [PATCH 3.16 116/212] drivers: hv: Turn off write permission on
 the hypercall page

3.16.44-rc1 review patch.  If anyone has any objections, please let me know.

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

From: "K. Y. Srinivasan" <kys@...rosoft.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 <kys@...rosoft.com>
Acked-by: Kees Cook <keescook@...omium.org>
Reported-by: Stephen Hemminger <stephen@...workplumber.org>
Tested-by: Stephen Hemminger <stephen@...workplumber.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[bwh: Backported to 3.16: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/hv/hv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -156,7 +156,7 @@ 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;