Fix potential crash with sys_move_pages

We incorrectly depended on the 'node_state/node_isset()' functions
testing the node range, rather than checking it explicitly.  That's not
reliable, even if it might often happen to work.  So do the proper
explicit test.

Reported-by: Marcus Meissner <meissner@suse.de>
Acked-and-tested-by: Brice Goglin <Brice.Goglin@inria.fr>
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index efddbf0926b..9a0db5bbabe 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -912,6 +912,9 @@ static int do_pages_move(struct mm_struct *mm, struct task_struct *task,
                                 goto out_pm;
 
                         err = -ENODEV;
+                        if (node < 0 || node >= MAX_NUMNODES)
+                                goto out_pm;
+
                         if (!node_state(node, N_HIGH_MEMORY))
                                 goto out_pm;