[PATCH 3.16 269/294] x86/xen: fix upper bound of pmd loop in xen_cleanhighmap()

[Ben Hutchings]

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

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

From: Juergen Gross <jgross@xxxxxxxx>

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@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 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;