From ba7c95ea3870fe7b847466d39a049ab6f156aa2c Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Tue, 24 Mar 2015 09:53:17 +1100 Subject: rhashtable: Fix sleeping inside RCU critical section in walk_stop The commit 963ecbd41a1026d99ec7537c050867428c397b89 ("rhashtable: Fix use-after-free in rhashtable_walk_stop") fixed a real bug but created another one because we may end up sleeping inside an RCU critical section. This patch fixes it properly by replacing the mutex with a spin lock that specifically protects the walker lists. Reported-by: Sasha Levin Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- lib/rhashtable.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'lib/rhashtable.c') diff --git a/lib/rhashtable.c b/lib/rhashtable.c index 7686c1e9934a..e96ad1a52c90 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -256,8 +256,10 @@ static int rhashtable_rehash_table(struct rhashtable *ht) /* Publish the new table pointer. */ rcu_assign_pointer(ht->tbl, new_tbl); + spin_lock(&ht->lock); list_for_each_entry(walker, &old_tbl->walkers, list) walker->tbl = NULL; + spin_unlock(&ht->lock); /* Wait for readers. All new readers will see the new * table, and thus no references to the old table will @@ -635,12 +637,12 @@ void rhashtable_walk_stop(struct rhashtable_iter *iter) ht = iter->ht; - mutex_lock(&ht->mutex); + spin_lock(&ht->lock); if (tbl->rehash < tbl->size) list_add(&iter->walker->list, &tbl->walkers); else iter->walker->tbl = NULL; - mutex_unlock(&ht->mutex); + spin_unlock(&ht->lock); iter->p = NULL; @@ -723,6 +725,7 @@ int rhashtable_init(struct rhashtable *ht, memset(ht, 0, sizeof(*ht)); mutex_init(&ht->mutex); + spin_lock_init(&ht->lock); memcpy(&ht->p, params, sizeof(*params)); if (params->min_size) -- cgit v1.2.3-55-g7522