From: Herbert Xu Date: Sun, 15 Mar 2015 10:12:04 +0000 (+1100) Subject: rhashtable: Fix use-after-free in rhashtable_walk_stop X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=963ecbd41a1026d99ec7537c050867428c397b89;p=linux-beck.git 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 Signed-off-by: David S. Miller --- diff --git a/lib/rhashtable.c b/lib/rhashtable.c index 9d53a46dcca9..b916679b3e3b 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -854,10 +854,8 @@ void rhashtable_walk_stop(struct rhashtable_iter *iter) 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 @@ void rhashtable_walk_stop(struct rhashtable_iter *iter) mutex_unlock(&ht->mutex); iter->p = NULL; + +out: + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(rhashtable_walk_stop);