From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yipeng Wang Subject: [PATCH v5 1/4] hash: fix race condition in iterate Date: Mon, 1 Oct 2018 11:34:59 -0700 Message-ID: <1538418902-154892-2-git-send-email-yipeng1.wang@intel.com> References: <1537993618-92630-1-git-send-email-yipeng1.wang@intel.com> <1538418902-154892-1-git-send-email-yipeng1.wang@intel.com> Cc: konstantin.ananyev@intel.com, dev@dpdk.org, yipeng1.wang@intel.com, honnappa.nagarahalli@arm.com, sameh.gobriel@intel.com To: bruce.richardson@intel.com Return-path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id 808904F90 for ; Tue, 2 Oct 2018 03:40:15 +0200 (CEST) In-Reply-To: <1538418902-154892-1-git-send-email-yipeng1.wang@intel.com> 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 rte_hash_iterate, the reader lock did not protect the while loop which checks empty entry. This created a race condition that the entry may become empty when enters the lock, then a wrong key data value would be read out. This commit reads out the position in the while condition, which makes sure that the position will not be changed to empty before entering the lock. Fixes: f2e3001b53ec ("hash: support read/write concurrency") Cc: stable@dpdk.org Signed-off-by: Yipeng Wang Reported-by: Honnappa Nagarahalli --- lib/librte_hash/rte_cuckoo_hash.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c index f7b86c8..da8ddf4 100644 --- a/lib/librte_hash/rte_cuckoo_hash.c +++ b/lib/librte_hash/rte_cuckoo_hash.c @@ -1318,7 +1318,7 @@ rte_hash_iterate(const struct rte_hash *h, const void **key, void **data, uint32 idx = *next % RTE_HASH_BUCKET_ENTRIES; /* If current position is empty, go to the next one */ - while (h->buckets[bucket_idx].key_idx[idx] == EMPTY_SLOT) { + while ((position = h->buckets[bucket_idx].key_idx[idx]) == EMPTY_SLOT) { (*next)++; /* End of table */ if (*next == total_entries) @@ -1326,9 +1326,8 @@ 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); - /* 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 + position * h->key_entry_size); /* Return key and data */ -- 2.7.4