[PATCH 4.4 26/35] Xen/x86: also check kernel mapping in set_foreign_p2m_mapping()

[Greg Kroah-Hartman]

From: Jan Beulich <jbeulich@xxxxxxxx>

commit b512e1b077e5ccdbd6e225b15d934ab12453b70a upstream.

We should not set up further state if either mapping failed; paying
attention to just the user mapping's status isn't enough.

Also use GNTST_okay instead of implying its value (zero).

This is part of XSA-361.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/xen/p2m.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -725,7 +725,8 @@ int set_foreign_p2m_mapping(struct gntta
 		unsigned long mfn, pfn;
 
 		/* Do not add to override if the map failed. */
-		if (map_ops[i].status)
+		if (map_ops[i].status != GNTST_okay ||
+		    (kmap_ops && kmap_ops[i].status != GNTST_okay))
 			continue;
 
 		if (map_ops[i].flags & GNTMAP_contains_pte) {