This patch is a backport of the following patch from the 2.6.15 branch
for 2.6.14 by Tim Yamin (plasmaroo@gentoo.org). See gentoo bug #117855.

---
X-Git-Url: http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=8f493d797bc1fe470377adc9d8775845427e240e

[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>

--- linux-2.6.14.orig/mm/mempolicy.c	2005-10-28 01:02:08.000000000 +0100
+++ linux-2.6.14/mm/mempolicy.c	2006-01-10 21:37:14.000000000 +0000
@@ -219,6 +219,10 @@
 	switch (mode) {
 	case MPOL_INTERLEAVE:
 		bitmap_copy(policy->v.nodes, nodes, MAX_NUMNODES);
+		if (bitmap_weight(nodes, MAX_NUMNODES) == 0) {
+			kmem_cache_free(policy_cache, policy);
+			return ERR_PTR(-EINVAL);
+		}
 		break;
 	case MPOL_PREFERRED:
 		policy->v.preferred_node = find_first_bit(nodes, MAX_NUMNODES);