From: K. Y. Srinivasan <kys@microsoft.com>
Date: Thu, 9 Feb 2017 01:30:56 +0000 (-0700)
Subject: drivers: hv: Turn off write permission on the hypercall page
X-Git-Tag: firefly_0821_release~176^2^2^2~37
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4cdfa660c82b57828ffcca94950eccc9458e18e4;p=firefly-linux-kernel-4.4.55.git

drivers: hv: Turn off write permission on the hypercall page

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@microsoft.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reported-by: Stephen Hemminger <stephen@networkplumber.org>
Tested-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 89fd0113aa5c..57c191798699 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -219,7 +219,7 @@ 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;