Commit d76b1590 authored Sep 03, 2009 by Eric Dumazet Committed by Pekka Enberg Sep 03, 2009

slub: Fix kmem_cache_destroy() with SLAB_DESTROY_BY_RCU



kmem_cache_destroy() should call rcu_barrier() *after* kmem_cache_close() and
*before* sysfs_slab_remove() or risk rcu_free_slab() being called after
kmem_cache is deleted (kfreed).

rmmod nf_conntrack can crash the machine because it has to kmem_cache_destroy()
a SLAB_DESTROY_BY_RCU enabled cache.

Cc: <stable@kernel.org>
Reported-by: Zdenek Kabelac <zdenek.kabelac@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

parent 326ba501

mm/slub.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -2594,8 +2594,6 @@ static inline int kmem_cache_close(struct kmem_cache *s)
		*/
		void kmem_cache_destroy(struct kmem_cache *s)
		{
		if (s->flags & SLAB_DESTROY_BY_RCU)
		rcu_barrier();
		down_write(&slub_lock);
		s->refcount--;
		if (!s->refcount) {
		@@ -2606,6 +2604,8 @@ void kmem_cache_destroy(struct kmem_cache *s)
		"still has objects.\n", s->name, __func__);
		dump_stack();
		}
		if (s->flags & SLAB_DESTROY_BY_RCU)
		rcu_barrier();
		sysfs_slab_remove(s);
		} else
		up_write(&slub_lock);