[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>

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index bec88c81244e0d4f9541f4098f5f8c8409ba455b..72f402cc9c9af77f6d6c765c166e35d0bb4764ae 100644 (file)
--- 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);