From: Herbert Xu Subject: Re: crypto: deadlock between crypto_alg_sem/rtnl_mutex/genl_mutex Date: Tue, 14 Mar 2017 18:25:57 +0800 Message-ID: <20170314102557.GA1225@gondor.apana.org.au> References: <20170314091649.GA711@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , linux-crypto@vger.kernel.org, LKML , Eric Dumazet , Cong Wang , netdev , syzkaller To: Dmitry Vyukov Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org On Tue, Mar 14, 2017 at 10:44:10AM +0100, Dmitry Vyukov wrote: > > Yes, please. > Disregarding some reports is not a good way long term. Please try this patch. ---8<--- Subject: netlink: Annotate nlk cb_mutex by protocol Currently all occurences of nlk->cb_mutex are annotated by lockdep as a single class. This causes a false lcokdep cycle involving genl and crypto_user. This patch fixes it by dividing cb_mutex into individual classes based on the netlink protocol. As genl and crypto_user do not use the same netlink protocol this breaks the false dependency loop. Reported-by: Dmitry Vyukov Signed-off-by: Herbert Xu diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 7b73c7c..596eaff 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -96,6 +96,44 @@ static inline int netlink_is_kernel(struct sock *sk) static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait); +static struct lock_class_key nlk_cb_mutex_keys[MAX_LINKS]; + +static const char *const nlk_cb_mutex_key_strings[MAX_LINKS + 1] = { + "nlk_cb_mutex-ROUTE", + "nlk_cb_mutex-1", + "nlk_cb_mutex-USERSOCK", + "nlk_cb_mutex-FIREWALL", + "nlk_cb_mutex-SOCK_DIAG", + "nlk_cb_mutex-NFLOG", + "nlk_cb_mutex-XFRM", + "nlk_cb_mutex-SELINUX", + "nlk_cb_mutex-ISCSI", + "nlk_cb_mutex-AUDIT", + "nlk_cb_mutex-FIB_LOOKUP", + "nlk_cb_mutex-CONNECTOR", + "nlk_cb_mutex-NETFILTER", + "nlk_cb_mutex-IP6_FW", + "nlk_cb_mutex-DNRTMSG", + "nlk_cb_mutex-KOBJECT_UEVENT", + "nlk_cb_mutex-GENERIC", + "nlk_cb_mutex-17", + "nlk_cb_mutex-SCSITRANSPORT", + "nlk_cb_mutex-ECRYPTFS", + "nlk_cb_mutex-RDMA", + "nlk_cb_mutex-CRYPTO", + "nlk_cb_mutex-SMC", + "nlk_cb_mutex-23", + "nlk_cb_mutex-24", + "nlk_cb_mutex-25", + "nlk_cb_mutex-26", + "nlk_cb_mutex-27", + "nlk_cb_mutex-28", + "nlk_cb_mutex-29", + "nlk_cb_mutex-30", + "nlk_cb_mutex-31", + "nlk_cb_mutex-MAX_LINKS" +}; + static int netlink_dump(struct sock *sk); static void netlink_skb_destructor(struct sk_buff *skb); @@ -585,6 +623,9 @@ static int __netlink_create(struct net *net, struct socket *sock, } else { nlk->cb_mutex = &nlk->cb_def_mutex; mutex_init(nlk->cb_mutex); + lockdep_set_class_and_name(nlk->cb_mutex, + nlk_cb_mutex_keys + protocol, + nlk_cb_mutex_key_strings[protocol]); } init_waitqueue_head(&nlk->wait); -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt