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rhashtable: Fix use-after-free in rhashtable_walk_stop 

The commit c4db8848af ("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>
This commit is contained in:
Herbert Xu 2015-03-15 21:12:04 +11:00 committed by David S. Miller
parent 0034de4193
commit 963ecbd41a
1 changed files with 4 additions and 3 deletions
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7
lib/rhashtable.c
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@ -854,10 +854,8 @@ void rhashtable_walk_stop(struct rhashtable_iter *iter)
struct rhashtable *ht; struct rhashtable *ht;
struct bucket_table *tbl = iter->walker->tbl; struct bucket_table *tbl = iter->walker->tbl;
rcu_read_unlock();
if (!tbl) if (!tbl)
return; goto out;
ht = iter->ht; ht = iter->ht;
@ -869,6 +867,9 @@ void rhashtable_walk_stop(struct rhashtable_iter *iter)
mutex_unlock(&ht->mutex); mutex_unlock(&ht->mutex);
iter->p = NULL; iter->p = NULL;
out:
rcu_read_unlock();
} }
EXPORT_SYMBOL_GPL(rhashtable_walk_stop); EXPORT_SYMBOL_GPL(rhashtable_walk_stop);