diff options
authorPaul Mackerras <paulus@samba.org>2014-12-02 15:59:48 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-03 09:36:04 -0800
commit7c3fbbdd04a681a1992ad6a3d7a36a63ff668753 (patch)
parentb724aa213df7aee08d57237ee0bbafffef09aea5 (diff)
slab: fix nodeid bounds check for non-contiguous node IDs
The bounds check for nodeid in ____cache_alloc_node gives false positives on machines where the node IDs are not contiguous, leading to a panic at boot time. For example, on a POWER8 machine the node IDs are typically 0, 1, 16 and 17. This means that num_online_nodes() returns 4, so when ____cache_alloc_node is called with nodeid = 16 the VM_BUG_ON triggers, like this: kernel BUG at /home/paulus/kernel/kvm/mm/slab.c:3079! Call Trace: .____cache_alloc_node+0x5c/0x270 (unreliable) .kmem_cache_alloc_node_trace+0xdc/0x360 .init_list+0x3c/0x128 .kmem_cache_init+0x1dc/0x258 .start_kernel+0x2a0/0x568 start_here_common+0x20/0xa8 To fix this, we instead compare the nodeid with MAX_NUMNODES, and additionally make sure it isn't negative (since nodeid is an int). The check is there mainly to protect the array dereference in the get_node() call in the next line, and the array being dereferenced is of size MAX_NUMNODES. If the nodeid is in range but invalid (for example if the node is off-line), the BUG_ON in the next line will catch that. Fixes: 14e50c6a9bc2 ("mm: slab: Verify the nodeid passed to ____cache_alloc_node") Signed-off-by: Paul Mackerras <paulus@samba.org> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Reviewed-by: Pekka Enberg <penberg@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/slab.c b/mm/slab.c
index eb2b2ea30130..f34e053ec46e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3076,7 +3076,7 @@ static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
void *obj;
int x;
- VM_BUG_ON(nodeid > num_online_nodes());
+ VM_BUG_ON(nodeid < 0 || nodeid >= MAX_NUMNODES);
n = get_node(cachep, nodeid);