diff options
| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-11-22 16:02:02 +0100 |
|---|---|---|
| committer | Pekka Enberg <penberg@kernel.org> | 2011-11-24 08:44:19 +0200 |
| commit | bc6697d8a506dedf09e8e9974ffa3a316183e608 (patch) | |
| tree | b54d3d45349fb8a00ce8a086da55a1ebf3394646 /mm | |
| parent | 42d623a8cd08eb93ab221d22cee5a62618895bbf (diff) | |
slub: avoid potential NULL dereference or corruption
show_slab_objects() can trigger NULL dereferences or memory corruption.
Another cpu can change its c->page to NULL or c->node to NUMA_NO_NODE
while we use them.
Use ACCESS_ONCE(c->page) and ACCESS_ONCE(c->node) to make sure this
cannot happen.
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/slub.c | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/mm/slub.c b/mm/slub.c index 2a9cfd72a3d7..ed3334d9b6da 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -4444,30 +4444,31 @@ static ssize_t show_slab_objects(struct kmem_cache *s, for_each_possible_cpu(cpu) { struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); + int node = ACCESS_ONCE(c->node); struct page *page; - if (!c || c->node < 0) + if (node < 0) continue; - - if (c->page) { - if (flags & SO_TOTAL) - x = c->page->objects; + page = ACCESS_ONCE(c->page); + if (page) { + if (flags & SO_TOTAL) + x = page->objects; else if (flags & SO_OBJECTS) - x = c->page->inuse; + x = page->inuse; else x = 1; total += x; - nodes[c->node] += x; + nodes[node] += x; } page = c->partial; if (page) { x = page->pobjects; - total += x; - nodes[c->node] += x; + total += x; + nodes[node] += x; } - per_cpu[c->node]++; + per_cpu[node]++; } } |