[PATCH] Make sure interleave masks have at least one node set

Otherwise a bad mem policy system call can confuse the interleaving
code into referencing undefined nodes.

Originally reported by Doug Chapman

I was told it's CVE-2005-3358
(one has to love these security people - they make everything sound important)

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index bec88c81244e..72f402cc9c9a 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -161,6 +161,10 @@ static struct mempolicy *mpol_new(int mode, nodemask_t *nodes)
         switch (mode) {
         case MPOL_INTERLEAVE:
                 policy->v.nodes = *nodes;
+                if (nodes_weight(*nodes) == 0) {
+                        kmem_cache_free(policy_cache, policy);
+                        return ERR_PTR(-EINVAL);
+                }
                 break;
         case MPOL_PREFERRED:
                 policy->v.preferred_node = first_node(*nodes);