Commit 8a0f5ccf authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

crypto: deadlock between crypto_alg_sem/rtnl_mutex/genl_mutex 



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: default avatarDmitry Vyukov <dvyukov@google.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 98d068ab

net/netlink/af_netlink.c

+41 −0
Original line number Diff line number Diff line
@@ -96,6 +96,44 @@ EXPORT_SYMBOL_GPL(nl_table); 


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);

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