mm: slab: Verify the nodeid passed to ____cache_alloc_node

If the nodeid is > num_online_nodes() this can cause an Oops and a
panic(). The purpose of this patch is to assert if this condition is
true to aid debugging efforts rather than some random NULL pointer
dereference or page fault.

This patch is in response to BZ#42967 [1].  Using VM_BUG_ON so it's used
only when CONFIG_DEBUG_VM is set, given that ____cache_alloc_node() is a
hot code path.

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=42967

Signed-off-by: Aaron Tomlin <[email protected]>
Reviewed-by: Rik van Riel <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
Acked-by: Rafael Aquini <[email protected]>
Acked-by: David Rientjes <[email protected]>
Signed-off-by: Pekka Enberg <[email protected]>
This commit is contained in:
Aaron Tomlin 2013-04-26 16:15:34 +01:00 • committed by Pekka Enberg
commit 14e50c6a9b

View file

@ -3289,6 +3289,7 @@ static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
void *obj;
int x;
VM_BUG_ON(nodeid > num_online_nodes());
n = cachep->node[nodeid];
BUG_ON(!n);