linux-kernel - [PATCH 3.16 269/294] x86/xen: fix upper bound of pmd loop in xen

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Date:   Mon, 06 Nov 2017 23:03:02 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "David Vrabel" <david.vrabel@...rix.com>,
        "Juergen Gross" <jgross@...e.com>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Arnd Bergmann" <arnd@...db.de>
Subject: [PATCH 3.16 269/294] x86/xen: fix upper bound of pmd loop in
 xen_cleanhighmap()

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

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

From: Juergen Gross <jgross@...e.com>

commit 1cf38741308c64d08553602b3374fb39224eeb5a upstream.

xen_cleanhighmap() is operating on level2_kernel_pgt only. The upper
bound of the loop setting non-kernel-image entries to zero should not
exceed the size of level2_kernel_pgt.

Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: David Vrabel <david.vrabel@...rix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/xen/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1187,7 +1187,7 @@ static void __init xen_cleanhighmap(unsi
 
 	/* NOTE: The loop is more greedy than the cleanup_highmap variant.
 	 * We include the PMD passed in on _both_ boundaries. */
-	for (; vaddr <= vaddr_end && (pmd < (level2_kernel_pgt + PAGE_SIZE));
+	for (; vaddr <= vaddr_end && (pmd < (level2_kernel_pgt + PTRS_PER_PMD));
 			pmd++, vaddr += PMD_SIZE) {
 		if (pmd_none(*pmd))
 			continue;