From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yonghong Song Subject: [PATCH bpf v2] bpf: fix memory leak in lpm_trie map_free callback function Date: Tue, 13 Feb 2018 19:00:21 -0800 Message-ID: <20180214030021.1927189-1-yhs@fb.com> Mime-Version: 1.0 Content-Type: text/plain Cc: To: , , Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:38138 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S966587AbeBNDAY (ORCPT ); Tue, 13 Feb 2018 22:00:24 -0500 Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.16.0.22/8.16.0.22) with SMTP id w1E2xIDx024649 for ; Tue, 13 Feb 2018 19:00:23 -0800 Received: from mail.thefacebook.com ([199.201.64.23]) by m0089730.ppops.net with ESMTP id 2g4csp803v-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Tue, 13 Feb 2018 19:00:23 -0800 Sender: netdev-owner@vger.kernel.org List-ID: There is a memory leak happening in lpm_trie map_free callback function trie_free. The trie structure itself does not get freed. Also, trie_free function did not do synchronize_rcu before freeing various data structures. This is incorrect as some rcu_read_lock region(s) for lookup, update, delete or get_next_key may not complete yet. The fix is to add synchronize_rcu in the beginning of trie_free. The useless spin_lock is removed from this function as well. Fixes: b95a5c4db09b ("bpf: add a longest prefix match trie map implementation") Reported-by: Mathieu Malaterre Reported-by: Alexei Starovoitov Tested-by: Mathieu Malaterre Signed-off-by: Yonghong Song --- kernel/bpf/lpm_trie.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) v1->v2: Make comments more precise and make label name more appropriate, as suggested by Daniel diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index 7b469d1..a75e02c 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -555,7 +555,10 @@ static void trie_free(struct bpf_map *map) struct lpm_trie_node __rcu **slot; struct lpm_trie_node *node; - raw_spin_lock(&trie->lock); + /* Wait for outstanding programs to complete + * update/lookup/delete/get_next_key and free the trie. + */ + synchronize_rcu(); /* Always start at the root and walk down to a node that has no * children. Then free that node, nullify its reference in the parent @@ -569,7 +572,7 @@ static void trie_free(struct bpf_map *map) node = rcu_dereference_protected(*slot, lockdep_is_held(&trie->lock)); if (!node) - goto unlock; + goto out; if (rcu_access_pointer(node->child[0])) { slot = &node->child[0]; @@ -587,8 +590,8 @@ static void trie_free(struct bpf_map *map) } } -unlock: - raw_spin_unlock(&trie->lock); +out: + kfree(trie); } static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) -- 2.9.5