rhashtable: Fix use-after-free in rhashtable_walk_stop
The commit c4db8848af6af92f90462258603be844baeab44d ("rhashtable:
Move future_tbl into struct bucket_table") introduced a use-after-
free bug in rhashtable_walk_stop because it dereferences tbl after
droping the RCU read lock.
This patch fixes it by moving the RCU read unlock down to the bottom
of rhashtable_walk_stop. In fact this was how I had it originally
but it got dropped while rearranging patches because this one
depended on the async freeing of bucket_table.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 9d53a46..b916679 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -854,10 +854,8 @@
struct rhashtable *ht;
struct bucket_table *tbl = iter->walker->tbl;
- rcu_read_unlock();
-
if (!tbl)
- return;
+ goto out;
ht = iter->ht;
@@ -869,6 +867,9 @@
mutex_unlock(&ht->mutex);
iter->p = NULL;
+
+out:
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(rhashtable_walk_stop);