linux-kernel - [PATCH 4.4 36/36] drivers: hv: Turn off write permission on the hypercall page

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Message-Id: <20170313083354.867331099@linuxfoundation.org>
Date:   Mon, 13 Mar 2017 16:39:36 +0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, "K. Y. Srinivasan" <kys@...rosoft.com>,
        Kees Cook <keescook@...omium.org>,
        Stephen Hemminger <stephen@...workplumber.org>
Subject: [PATCH 4.4 36/36] drivers: hv: Turn off write permission on the hypercall page

4.4-stable 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>

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

--- 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;