diff options
| author | Herbert Xu <herbert@gondor.apana.org.au> | 2015-03-24 09:53:17 +1100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-03-23 22:16:07 -0400 |
| commit | ba7c95ea3870fe7b847466d39a049ab6f156aa2c (patch) | |
| tree | 8fed9deb6a4a0c1f52634ff0bd07fb6a0edb8dde | |
| parent | ce046c568cbfb4734583131086f88cfe993c01d0 (diff) | |
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 <sasha.levin@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/rhashtable.h | 2 | ||||
| -rw-r--r-- | lib/rhashtable.c | 7 |
2 files changed, 7 insertions, 2 deletions
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index f9ecf32bce55..d7be9cb0e91f 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -133,6 +133,7 @@ struct rhashtable_params { * @p: Configuration parameters * @run_work: Deferred worker to expand/shrink asynchronously * @mutex: Mutex to protect current/future table swapping + * @lock: Spin lock to protect walker list * @being_destroyed: True if table is set up for destruction */ struct rhashtable { @@ -144,6 +145,7 @@ struct rhashtable { struct rhashtable_params p; struct work_struct run_work; struct mutex mutex; + spinlock_t lock; }; /** 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) |