ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 459 insertions, 0 deletions

diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c
new file mode 100644
index 000000000..1272d49cd
--- /dev/null
+++ b/net/phonet/pn_dev.c
@@ -0,0 +1,459 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * File: pn_dev.c
+ *
+ * Phonet network device
+ *
+ * Copyright (C) 2008 Nokia Corporation.
+ *
+ * Authors: Sakari Ailus <sakari.ailus@nokia.com>
+ *          Rémi Denis-Courmont
+ */
+
+#include <linux/kernel.h>
+#include <linux/net.h>
+#include <linux/slab.h>
+#include <linux/netdevice.h>
+#include <linux/phonet.h>
+#include <linux/proc_fs.h>
+#include <linux/if_arp.h>
+#include <net/sock.h>
+#include <net/netns/generic.h>
+#include <net/phonet/pn_dev.h>
+
+struct phonet_routes {
+	spinlock_t		lock;
+	struct net_device __rcu	*table[64];
+};
+
+struct phonet_net {
+	struct phonet_device_list pndevs;
+	struct phonet_routes routes;
+};
+
+static unsigned int phonet_net_id __read_mostly;
+
+static struct phonet_net *phonet_pernet(struct net *net)
+{
+	return net_generic(net, phonet_net_id);
+}
+
+struct phonet_device_list *phonet_device_list(struct net *net)
+{
+	struct phonet_net *pnn = phonet_pernet(net);
+	return &pnn->pndevs;
+}
+
+/* Allocate new Phonet device. */
+static struct phonet_device *__phonet_device_alloc(struct net_device *dev)
+{
+	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
+	struct phonet_device *pnd = kmalloc_obj(*pnd, GFP_ATOMIC);
+	if (pnd == NULL)
+		return NULL;
+	pnd->netdev = dev;
+	bitmap_zero(pnd->addrs, 64);
+
+	lockdep_assert_held(&pndevs->lock);
+	list_add_rcu(&pnd->list, &pndevs->list);
+	return pnd;
+}
+
+static struct phonet_device *__phonet_get(struct net_device *dev)
+{
+	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
+	struct phonet_device *pnd;
+
+	lockdep_assert_held(&pndevs->lock);
+
+	list_for_each_entry(pnd, &pndevs->list, list) {
+		if (pnd->netdev == dev)
+			return pnd;
+	}
+	return NULL;
+}
+
+static struct phonet_device *__phonet_get_rcu(struct net_device *dev)
+{
+	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
+	struct phonet_device *pnd;
+
+	list_for_each_entry_rcu(pnd, &pndevs->list, list) {
+		if (pnd->netdev == dev)
+			return pnd;
+	}
+	return NULL;
+}
+
+static void phonet_device_destroy(struct net_device *dev)
+{
+	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
+	struct phonet_device *pnd;
+
+	ASSERT_RTNL();
+
+	spin_lock(&pndevs->lock);
+
+	pnd = __phonet_get(dev);
+	if (pnd)
+		list_del_rcu(&pnd->list);
+
+	spin_unlock(&pndevs->lock);
+
+	if (pnd) {
+		struct net *net = dev_net(dev);
+		u32 ifindex = dev->ifindex;
+		u8 addr;
+
+		for_each_set_bit(addr, pnd->addrs, 64)
+			phonet_address_notify(net, RTM_DELADDR, ifindex, addr);
+
+		kfree_rcu(pnd, rcu);
+	}
+}
+
+struct net_device *phonet_device_get(struct net *net)
+{
+	struct phonet_device_list *pndevs = phonet_device_list(net);
+	struct phonet_device *pnd;
+	struct net_device *dev = NULL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(pnd, &pndevs->list, list) {
+		dev = pnd->netdev;
+		BUG_ON(!dev);
+
+		if ((dev->reg_state == NETREG_REGISTERED) &&
+			((pnd->netdev->flags & IFF_UP)) == IFF_UP)
+			break;
+		dev = NULL;
+	}
+	dev_hold(dev);
+	rcu_read_unlock();
+	return dev;
+}
+
+int phonet_address_add(struct net_device *dev, u8 addr)
+{
+	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
+	struct phonet_device *pnd;
+	int err = 0;
+
+	spin_lock(&pndevs->lock);
+
+	/* Find or create Phonet-specific device data */
+	pnd = __phonet_get(dev);
+	if (pnd == NULL)
+		pnd = __phonet_device_alloc(dev);
+	if (unlikely(pnd == NULL))
+		err = -ENOMEM;
+	else if (test_and_set_bit(addr >> 2, pnd->addrs))
+		err = -EEXIST;
+
+	spin_unlock(&pndevs->lock);
+
+	return err;
+}
+
+int phonet_address_del(struct net_device *dev, u8 addr)
+{
+	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
+	struct phonet_device *pnd;
+	int err = 0;
+
+	spin_lock(&pndevs->lock);
+
+	pnd = __phonet_get(dev);
+	if (!pnd || !test_and_clear_bit(addr >> 2, pnd->addrs)) {
+		err = -EADDRNOTAVAIL;
+		pnd = NULL;
+	} else if (bitmap_empty(pnd->addrs, 64))
+		list_del_rcu(&pnd->list);
+	else
+		pnd = NULL;
+
+	spin_unlock(&pndevs->lock);
+
+	if (pnd)
+		kfree_rcu(pnd, rcu);
+
+	return err;
+}
+
+/* Gets a source address toward a destination, through a interface. */
+u8 phonet_address_get(struct net_device *dev, u8 daddr)
+{
+	struct phonet_device *pnd;
+	u8 saddr;
+
+	rcu_read_lock();
+	pnd = __phonet_get_rcu(dev);
+	if (pnd) {
+		BUG_ON(bitmap_empty(pnd->addrs, 64));
+
+		/* Use same source address as destination, if possible */
+		if (test_bit(daddr >> 2, pnd->addrs))
+			saddr = daddr;
+		else
+			saddr = find_first_bit(pnd->addrs, 64) << 2;
+	} else
+		saddr = PN_NO_ADDR;
+	rcu_read_unlock();
+
+	if (saddr == PN_NO_ADDR) {
+		/* Fallback to another device */
+		struct net_device *def_dev;
+
+		def_dev = phonet_device_get(dev_net(dev));
+		if (def_dev) {
+			if (def_dev != dev)
+				saddr = phonet_address_get(def_dev, daddr);
+			dev_put(def_dev);
+		}
+	}
+	return saddr;
+}
+
+int phonet_address_lookup(struct net *net, u8 addr)
+{
+	struct phonet_device_list *pndevs = phonet_device_list(net);
+	struct phonet_device *pnd;
+	int err = -EADDRNOTAVAIL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(pnd, &pndevs->list, list) {
+		/* Don't allow unregistering devices! */
+		if ((pnd->netdev->reg_state != NETREG_REGISTERED) ||
+				((pnd->netdev->flags & IFF_UP)) != IFF_UP)
+			continue;
+
+		if (test_bit(addr >> 2, pnd->addrs)) {
+			err = 0;
+			goto found;
+		}
+	}
+found:
+	rcu_read_unlock();
+	return err;
+}
+
+/* automatically configure a Phonet device, if supported */
+static int phonet_device_autoconf(struct net_device *dev)
+{
+	struct if_phonet_req req;
+	int ret;
+
+	if (!dev->netdev_ops->ndo_siocdevprivate)
+		return -EOPNOTSUPP;
+
+	ret = dev->netdev_ops->ndo_siocdevprivate(dev, (struct ifreq *)&req,
+						  NULL, SIOCPNGAUTOCONF);
+	if (ret < 0)
+		return ret;
+
+	ASSERT_RTNL();
+	ret = phonet_address_add(dev, req.ifr_phonet_autoconf.device);
+	if (ret)
+		return ret;
+
+	phonet_address_notify(dev_net(dev), RTM_NEWADDR, dev->ifindex,
+			      req.ifr_phonet_autoconf.device);
+	return 0;
+}
+
+static void phonet_route_autodel(struct net_device *dev)
+{
+	struct net *net = dev_net(dev);
+	DECLARE_BITMAP(deleted, 64);
+	u32 ifindex = dev->ifindex;
+	struct phonet_net *pnn;
+	unsigned int i;
+
+	pnn = phonet_pernet(net);
+
+	/* Remove left-over Phonet routes */
+	bitmap_zero(deleted, 64);
+
+	spin_lock(&pnn->routes.lock);
+	for (i = 0; i < 64; i++) {
+		if (rcu_access_pointer(pnn->routes.table[i]) == dev) {
+			RCU_INIT_POINTER(pnn->routes.table[i], NULL);
+			set_bit(i, deleted);
+		}
+	}
+	spin_unlock(&pnn->routes.lock);
+
+	if (bitmap_empty(deleted, 64))
+		return; /* short-circuit RCU */
+	synchronize_rcu();
+	for_each_set_bit(i, deleted, 64) {
+		rtm_phonet_notify(net, RTM_DELROUTE, ifindex, i);
+		dev_put(dev);
+	}
+}
+
+/* notify Phonet of device events */
+static int phonet_device_notify(struct notifier_block *me, unsigned long what,
+				void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+
+	switch (what) {
+	case NETDEV_REGISTER:
+		if (dev->type == ARPHRD_PHONET)
+			phonet_device_autoconf(dev);
+		break;
+	case NETDEV_UNREGISTER:
+		phonet_device_destroy(dev);
+		phonet_route_autodel(dev);
+		break;
+	}
+	return 0;
+
+}
+
+static struct notifier_block phonet_device_notifier = {
+	.notifier_call = phonet_device_notify,
+	.priority = 0,
+};
+
+/* Per-namespace Phonet devices handling */
+static int __net_init phonet_init_net(struct net *net)
+{
+	struct phonet_net *pnn = phonet_pernet(net);
+
+	if (!proc_create_net("phonet", 0, net->proc_net, &pn_sock_seq_ops,
+			sizeof(struct seq_net_private)))
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&pnn->pndevs.list);
+	spin_lock_init(&pnn->pndevs.lock);
+	spin_lock_init(&pnn->routes.lock);
+	return 0;
+}
+
+static void __net_exit phonet_exit_net(struct net *net)
+{
+	struct phonet_net *pnn = phonet_pernet(net);
+
+	remove_proc_entry("phonet", net->proc_net);
+	WARN_ON_ONCE(!list_empty(&pnn->pndevs.list));
+}
+
+static struct pernet_operations phonet_net_ops = {
+	.init = phonet_init_net,
+	.exit = phonet_exit_net,
+	.id   = &phonet_net_id,
+	.size = sizeof(struct phonet_net),
+};
+
+/* Initialize Phonet devices list */
+int __init phonet_device_init(void)
+{
+	int err;
+
+	err = register_pernet_subsys(&phonet_net_ops);
+	if (err)
+		return err;
+
+	if (!proc_create_net("pnresource", 0, init_net.proc_net,
+			     &pn_res_seq_ops, sizeof(struct seq_net_private))) {
+		err = -ENOMEM;
+		goto err_pernet;
+	}
+
+	err = register_netdevice_notifier(&phonet_device_notifier);
+	if (err)
+		goto err_proc;
+
+	err = phonet_netlink_register();
+	if (err)
+		goto err_notifier;
+
+	return 0;
+
+err_notifier:
+	unregister_netdevice_notifier(&phonet_device_notifier);
+err_proc:
+	remove_proc_entry("pnresource", init_net.proc_net);
+err_pernet:
+	unregister_pernet_subsys(&phonet_net_ops);
+	return err;
+}
+
+void phonet_device_exit(void)
+{
+	rtnl_unregister_all(PF_PHONET);
+	unregister_netdevice_notifier(&phonet_device_notifier);
+	remove_proc_entry("pnresource", init_net.proc_net);
+	unregister_pernet_subsys(&phonet_net_ops);
+}
+
+int phonet_route_add(struct net_device *dev, u8 daddr)
+{
+	struct phonet_net *pnn = phonet_pernet(dev_net(dev));
+	struct phonet_routes *routes = &pnn->routes;
+	int err = -EEXIST;
+
+	daddr = daddr >> 2;
+
+	spin_lock(&routes->lock);
+	if (routes->table[daddr] == NULL) {
+		rcu_assign_pointer(routes->table[daddr], dev);
+		dev_hold(dev);
+		err = 0;
+	}
+	spin_unlock(&routes->lock);
+
+	return err;
+}
+
+int phonet_route_del(struct net_device *dev, u8 daddr)
+{
+	struct phonet_net *pnn = phonet_pernet(dev_net(dev));
+	struct phonet_routes *routes = &pnn->routes;
+
+	daddr = daddr >> 2;
+
+	spin_lock(&routes->lock);
+	if (rcu_access_pointer(routes->table[daddr]) == dev)
+		RCU_INIT_POINTER(routes->table[daddr], NULL);
+	else
+		dev = NULL;
+	spin_unlock(&routes->lock);
+
+	if (!dev)
+		return -ENOENT;
+
+	/* Note : our caller must call synchronize_rcu() and dev_put(dev) */
+
+	return 0;
+}
+
+struct net_device *phonet_route_get_rcu(struct net *net, u8 daddr)
+{
+	struct phonet_net *pnn = phonet_pernet(net);
+	struct phonet_routes *routes = &pnn->routes;
+	struct net_device *dev;
+
+	daddr >>= 2;
+	dev = rcu_dereference(routes->table[daddr]);
+	return dev;
+}
+
+struct net_device *phonet_route_output(struct net *net, u8 daddr)
+{
+	struct phonet_net *pnn = phonet_pernet(net);
+	struct phonet_routes *routes = &pnn->routes;
+	struct net_device *dev;
+
+	daddr >>= 2;
+	rcu_read_lock();
+	dev = rcu_dereference(routes->table[daddr]);
+	dev_hold(dev);
+	rcu_read_unlock();
+
+	if (!dev)
+		dev = phonet_device_get(net); /* Default route */
+	return dev;
+}