From mboxrd@z Thu Jan 1 00:00:00 1970 From: Qiaobin Fu Subject: [PATCH v4 1/2] hash table: fix a bug in rte_hash_iterate() Date: Tue, 9 Oct 2018 19:29:06 +0000 Message-ID: <20181009192907.85650-1-qiaobinf@bu.edu> References: <20180831165101.20026-1-qiaobinf@bu.edu> Cc: dev@dpdk.org, doucette@bu.edu, keith.wiles@intel.com, sameh.gobriel@intel.com, charlie.tai@intel.com, stephen@networkplumber.org, nd@arm.com, honnappa.nagarahalli@arm.com, yipeng1.wang@intel.com, michel@digirati.com.br, qiaobinf@bu.edu To: bruce.richardson@intel.com, pablo.de.lara.guarch@intel.com Return-path: Received: from relay68.bu.edu (relay68.bu.edu [128.197.228.73]) by dpdk.org (Postfix) with ESMTP id 420181B3C0 for ; Tue, 9 Oct 2018 21:30:21 +0200 (CEST) In-Reply-To: <20180831165101.20026-1-qiaobinf@bu.edu> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" In current implementation of rte_hash_iterate(), it tries to obtain the lock after the while loop. However, this may lead to a bug. Notice the following racing condition: 1. The while loop above finishes because it finds a not empty slot. But it does so without a lock. 2. Then we get the lock. 3. The position that was once not empty is now empty. BUG because next_key is invalid. This patch fixes this small bug. Signed-off-by: Qiaobin Fu Reviewed-by: Michel Machado --- lib/librte_hash/rte_cuckoo_hash.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c index f7b86c8c9..a3e76684d 100644 --- a/lib/librte_hash/rte_cuckoo_hash.c +++ b/lib/librte_hash/rte_cuckoo_hash.c @@ -1317,16 +1317,18 @@ rte_hash_iterate(const struct rte_hash *h, const void **key, void **data, uint32 bucket_idx = *next / RTE_HASH_BUCKET_ENTRIES; idx = *next % RTE_HASH_BUCKET_ENTRIES; + __hash_rw_reader_lock(h); /* If current position is empty, go to the next one */ while (h->buckets[bucket_idx].key_idx[idx] == EMPTY_SLOT) { (*next)++; /* End of table */ - if (*next == total_entries) + if (*next == total_entries) { + __hash_rw_reader_unlock(h); return -ENOENT; + } bucket_idx = *next / RTE_HASH_BUCKET_ENTRIES; idx = *next % RTE_HASH_BUCKET_ENTRIES; } - __hash_rw_reader_lock(h); /* Get position of entry in key table */ position = h->buckets[bucket_idx].key_idx[idx]; next_key = (struct rte_hash_key *) ((char *)h->key_store + -- 2.17.1