This is a note to let you know that I've just added the patch titled
mptcp: fix lockdep false positive in mptcp_pm_nl_create_listen_socket()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mptcp-fix-lockdep-false-positive-in-mptcp_pm_nl_create_listen_socket.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From cee4034a3db1d30c3243dd51506a9d4ab1a849fa Mon Sep 17 00:00:00 2001
From: Paolo Abeni <pabeni@xxxxxxxxxx>
Date: Thu, 9 Mar 2023 15:50:04 +0100
Subject: mptcp: fix lockdep false positive in mptcp_pm_nl_create_listen_socket()
From: Paolo Abeni <pabeni@xxxxxxxxxx>
commit cee4034a3db1d30c3243dd51506a9d4ab1a849fa upstream.
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: ad2171009d96 ("mptcp: fix locking for in-kernel listener creation")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Christoph Paasch <cpaasch@xxxxxxxxx>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/354
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
Tested-by: Christoph Paasch <cpaasch@xxxxxxxxx>
Signed-off-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/mptcp/pm_netlink.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -886,9 +886,13 @@ out:
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;
@@ -907,6 +911,18 @@ static int mptcp_pm_nl_create_listen_soc
goto out;
}
+ /* 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);
Patches currently in stable-queue which might be from pabeni@xxxxxxxxxx are
queue-5.15/mptcp-fix-possible-deadlock-in-subflow_error_report.patch
queue-5.15/mptcp-avoid-setting-tcp_close-state-twice.patch
queue-5.15/mptcp-fix-lockdep-false-positive-in-mptcp_pm_nl_create_listen_socket.patch
