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 <[email protected]>
Acked-and-tested-by: Brice Goglin <[email protected]>
Acked-by: Hugh Dickins <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 3 insertions, 0 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index efddbf0926b2..9a0db5bbabe4 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;