Commit cee4034a authored by Paolo Abeni's avatar Paolo Abeni Committed by Jakub Kicinski
Browse files

mptcp: fix lockdep false positive in mptcp_pm_nl_create_listen_socket() 



Christoph reports a lockdep splat in the mptcp_subflow_create_socket()
error path, when such function is invoked by
mptcp_pm_nl_create_listen_socket().

Such code path acquires two separates, nested socket lock, with the
internal lock operation lacking the "nested" annotation. Adding that
in sock_release() for mptcp's sake only could be confusing.

Instead just add a new lockclass to the in-kernel msk socket,
re-initializing the lockdep infra after the socket creation.

Fixes: ad217100 ("mptcp: fix locking for in-kernel listener creation")
Cc: stable@vger.kernel.org
Reported-by: default avatarChristoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/354


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Reviewed-by: default avatarMatthieu Baerts <matthieu.baerts@tessares.net>
Tested-by: default avatarChristoph Paasch <cpaasch@apple.com>
Signed-off-by: default avatarMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 3ba14528

net/mptcp/pm_netlink.c

+16 −0
Original line number Diff line number Diff line
@@ -997,9 +997,13 @@ static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet, 
	return ret;

}



static struct lock_class_key mptcp_slock_keys[2];

static struct lock_class_key mptcp_keys[2];



static int mptcp_pm_nl_create_listen_socket(struct sock *sk,

					    struct mptcp_pm_addr_entry *entry)

{

	bool is_ipv6 = sk->sk_family == AF_INET6;

	int addrlen = sizeof(struct sockaddr_in);

	struct sockaddr_storage addr;

	struct socket *ssock;
@@ -1016,6 +1020,18 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk, 
	if (!newsk)

		return -EINVAL;



	/* The subflow socket lock is acquired in a nested to the msk one

	 * in several places, even by the TCP stack, and this msk is a kernel

	 * socket: lockdep complains. Instead of propagating the _nested

	 * modifiers in several places, re-init the lock class for the msk

	 * socket to an mptcp specific one.

	 */

	sock_lock_init_class_and_name(newsk,

				      is_ipv6 ? "mlock-AF_INET6" : "mlock-AF_INET",

				      &mptcp_slock_keys[is_ipv6],

				      is_ipv6 ? "msk_lock-AF_INET6" : "msk_lock-AF_INET",

				      &mptcp_keys[is_ipv6]);



	lock_sock(newsk);

	ssock = __mptcp_nmpc_socket(mptcp_sk(newsk));

	release_sock(newsk);