linux-kernel - [PATCH 3.10 044/319] x86/xen: fix upper bound of pmd loop in xen

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Date:   Sun,  5 Feb 2017 20:20:31 +0100
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Juergen Gross <jgross@...e.com>,
        David Vrabel <david.vrabel@...rix.com>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 044/319] x86/xen: fix upper bound of pmd loop in xen_cleanhighmap()

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: Willy Tarreau <w@....eu>
---
 arch/x86/xen/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index fdc3ba2..53b061c 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1187,7 +1187,7 @@ static void __init xen_cleanhighmap(unsigned long vaddr,
 
 	/* 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;
-- 
2.8.0.rc2.1.gbe9624a