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, 162 insertions, 0 deletions

diff --git a/net/atm/pvc.c b/net/atm/pvc.c
new file mode 100644
index 000000000..8b2c3e515
--- /dev/null
+++ b/net/atm/pvc.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0
+/* net/atm/pvc.c - ATM PVC sockets */
+
+/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */
+
+
+#include <linux/net.h>		/* struct socket, struct proto_ops */
+#include <linux/atm.h>		/* ATM stuff */
+#include <linux/atmdev.h>	/* ATM devices */
+#include <linux/errno.h>	/* error codes */
+#include <linux/kernel.h>	/* printk */
+#include <linux/init.h>
+#include <linux/skbuff.h>
+#include <linux/bitops.h>
+#include <linux/export.h>
+#include <net/sock.h>		/* for sock_no_* */
+
+#include "resources.h"		/* devs and vccs */
+#include "common.h"		/* common for PVCs and SVCs */
+
+
+static int pvc_shutdown(struct socket *sock, int how)
+{
+	return 0;
+}
+
+static int pvc_bind(struct socket *sock, struct sockaddr_unsized *sockaddr,
+		    int sockaddr_len)
+{
+	struct sock *sk = sock->sk;
+	struct sockaddr_atmpvc *addr;
+	struct atm_vcc *vcc;
+	int error;
+
+	if (sockaddr_len != sizeof(struct sockaddr_atmpvc))
+		return -EINVAL;
+	addr = (struct sockaddr_atmpvc *)sockaddr;
+	if (addr->sap_family != AF_ATMPVC)
+		return -EAFNOSUPPORT;
+	lock_sock(sk);
+	vcc = ATM_SD(sock);
+	if (!test_bit(ATM_VF_HASQOS, &vcc->flags)) {
+		error = -EBADFD;
+		goto out;
+	}
+	if (test_bit(ATM_VF_PARTIAL, &vcc->flags)) {
+		if (vcc->vpi != ATM_VPI_UNSPEC)
+			addr->sap_addr.vpi = vcc->vpi;
+		if (vcc->vci != ATM_VCI_UNSPEC)
+			addr->sap_addr.vci = vcc->vci;
+	}
+	error = vcc_connect(sock, addr->sap_addr.itf, addr->sap_addr.vpi,
+			    addr->sap_addr.vci);
+out:
+	release_sock(sk);
+	return error;
+}
+
+static int pvc_connect(struct socket *sock, struct sockaddr_unsized *sockaddr,
+		       int sockaddr_len, int flags)
+{
+	return pvc_bind(sock, sockaddr, sockaddr_len);
+}
+
+static int pvc_setsockopt(struct socket *sock, int level, int optname,
+			  sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = sock->sk;
+	int error;
+
+	lock_sock(sk);
+	error = vcc_setsockopt(sock, level, optname, optval, optlen);
+	release_sock(sk);
+	return error;
+}
+
+static int pvc_getsockopt(struct socket *sock, int level, int optname,
+			  sockopt_t *opt)
+{
+	struct sock *sk = sock->sk;
+	int error;
+
+	lock_sock(sk);
+	error = vcc_getsockopt(sock, level, optname, opt);
+	release_sock(sk);
+	return error;
+}
+
+static int pvc_getname(struct socket *sock, struct sockaddr *sockaddr,
+		       int peer)
+{
+	struct sockaddr_atmpvc *addr;
+	struct atm_vcc *vcc = ATM_SD(sock);
+
+	if (!vcc->dev || !test_bit(ATM_VF_ADDR, &vcc->flags))
+		return -ENOTCONN;
+	addr = (struct sockaddr_atmpvc *)sockaddr;
+	memset(addr, 0, sizeof(*addr));
+	addr->sap_family = AF_ATMPVC;
+	addr->sap_addr.itf = vcc->dev->number;
+	addr->sap_addr.vpi = vcc->vpi;
+	addr->sap_addr.vci = vcc->vci;
+	return sizeof(struct sockaddr_atmpvc);
+}
+
+static const struct proto_ops pvc_proto_ops = {
+	.family =	PF_ATMPVC,
+	.owner =	THIS_MODULE,
+
+	.release =	vcc_release,
+	.bind =		pvc_bind,
+	.connect =	pvc_connect,
+	.socketpair =	sock_no_socketpair,
+	.accept =	sock_no_accept,
+	.getname =	pvc_getname,
+	.poll =		vcc_poll,
+	.ioctl =	vcc_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = vcc_compat_ioctl,
+#endif
+	.gettstamp =	sock_gettstamp,
+	.listen =	sock_no_listen,
+	.shutdown =	pvc_shutdown,
+	.setsockopt =	pvc_setsockopt,
+	.getsockopt_iter = pvc_getsockopt,
+	.sendmsg =	vcc_sendmsg,
+	.recvmsg =	vcc_recvmsg,
+	.mmap =		sock_no_mmap,
+};
+
+
+static int pvc_create(struct net *net, struct socket *sock, int protocol,
+		      int kern)
+{
+	if (net != &init_net)
+		return -EAFNOSUPPORT;
+
+	sock->ops = &pvc_proto_ops;
+	return vcc_create(net, sock, protocol, PF_ATMPVC, kern);
+}
+
+static const struct net_proto_family pvc_family_ops = {
+	.family = PF_ATMPVC,
+	.create = pvc_create,
+	.owner = THIS_MODULE,
+};
+
+
+/*
+ *	Initialize the ATM PVC protocol family
+ */
+
+
+int __init atmpvc_init(void)
+{
+	return sock_register(&pvc_family_ops);
+}
+
+void atmpvc_exit(void)
+{
+	sock_unregister(PF_ATMPVC);
+}