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, 293 insertions, 0 deletions

diff --git a/net/atm/ioctl.c b/net/atm/ioctl.c
new file mode 100644
index 000000000..194587fc1
--- /dev/null
+++ b/net/atm/ioctl.c
@@ -0,0 +1,293 @@
+// SPDX-License-Identifier: GPL-2.0
+/* ATM ioctl handling */
+
+/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */
+/* 2003 John Levon  <levon@movementarian.org> */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
+
+#include <linux/module.h>
+#include <linux/kmod.h>
+#include <linux/net.h>		/* struct socket, struct proto_ops */
+#include <linux/atm.h>		/* ATM stuff */
+#include <linux/atmdev.h>
+#include <linux/capability.h>
+#include <linux/mutex.h>
+#include <asm/ioctls.h>
+#include <net/compat.h>
+
+#include "resources.h"
+#include "common.h"
+
+
+static DEFINE_MUTEX(ioctl_mutex);
+static LIST_HEAD(ioctl_list);
+
+
+void register_atm_ioctl(struct atm_ioctl *ioctl)
+{
+	mutex_lock(&ioctl_mutex);
+	list_add_tail(&ioctl->list, &ioctl_list);
+	mutex_unlock(&ioctl_mutex);
+}
+EXPORT_SYMBOL(register_atm_ioctl);
+
+void deregister_atm_ioctl(struct atm_ioctl *ioctl)
+{
+	mutex_lock(&ioctl_mutex);
+	list_del(&ioctl->list);
+	mutex_unlock(&ioctl_mutex);
+}
+EXPORT_SYMBOL(deregister_atm_ioctl);
+
+static int do_vcc_ioctl(struct socket *sock, unsigned int cmd,
+			unsigned long arg, int compat)
+{
+	struct sock *sk = sock->sk;
+	struct atm_vcc *vcc;
+	int error;
+	struct list_head *pos;
+	void __user *argp = (void __user *)arg;
+	void __user *buf;
+	int __user *len;
+
+	vcc = ATM_SD(sock);
+	switch (cmd) {
+	case SIOCOUTQ:
+		if (sock->state != SS_CONNECTED ||
+		    !test_bit(ATM_VF_READY, &vcc->flags)) {
+			error =  -EINVAL;
+			goto done;
+		}
+		error = put_user(sk->sk_sndbuf - sk_wmem_alloc_get(sk),
+				 (int __user *)argp);
+		goto done;
+	case SIOCINQ:
+	{
+		struct sk_buff *skb;
+		int amount;
+
+		if (sock->state != SS_CONNECTED) {
+			error = -EINVAL;
+			goto done;
+		}
+		spin_lock_irq(&sk->sk_receive_queue.lock);
+		skb = skb_peek(&sk->sk_receive_queue);
+		amount = skb ? skb->len : 0;
+		spin_unlock_irq(&sk->sk_receive_queue.lock);
+		error = put_user(amount, (int __user *)argp);
+		goto done;
+	}
+	case ATM_SETSC:
+		net_warn_ratelimited("ATM_SETSC is obsolete; used by %s:%d\n",
+				     current->comm, task_pid_nr(current));
+		error = 0;
+		goto done;
+	case ATM_SETBACKEND:
+	case ATM_NEWBACKENDIF:
+	{
+		atm_backend_t backend;
+		error = get_user(backend, (atm_backend_t __user *)argp);
+		if (error)
+			goto done;
+		switch (backend) {
+		case ATM_BACKEND_PPP:
+			request_module("pppoatm");
+			break;
+		case ATM_BACKEND_BR2684:
+			request_module("br2684");
+			break;
+		}
+		break;
+	}
+	}
+
+	error = -ENOIOCTLCMD;
+
+	mutex_lock(&ioctl_mutex);
+	list_for_each(pos, &ioctl_list) {
+		struct atm_ioctl *ic = list_entry(pos, struct atm_ioctl, list);
+		if (try_module_get(ic->owner)) {
+			error = ic->ioctl(sock, cmd, arg);
+			module_put(ic->owner);
+			if (error != -ENOIOCTLCMD)
+				break;
+		}
+	}
+	mutex_unlock(&ioctl_mutex);
+
+	if (error != -ENOIOCTLCMD)
+		goto done;
+
+	if (cmd == ATM_GETNAMES) {
+		if (IS_ENABLED(CONFIG_COMPAT) && compat) {
+#ifdef CONFIG_COMPAT
+			struct compat_atm_iobuf __user *ciobuf = argp;
+			compat_uptr_t cbuf;
+			len = &ciobuf->length;
+			if (get_user(cbuf, &ciobuf->buffer))
+				return -EFAULT;
+			buf = compat_ptr(cbuf);
+#endif
+		} else {
+			struct atm_iobuf __user *iobuf = argp;
+			len = &iobuf->length;
+			if (get_user(buf, &iobuf->buffer))
+				return -EFAULT;
+		}
+		error = atm_getnames(buf, len);
+	} else {
+		int number;
+
+		if (IS_ENABLED(CONFIG_COMPAT) && compat) {
+#ifdef CONFIG_COMPAT
+			struct compat_atmif_sioc __user *csioc = argp;
+			compat_uptr_t carg;
+
+			len = &csioc->length;
+			if (get_user(carg, &csioc->arg))
+				return -EFAULT;
+			buf = compat_ptr(carg);
+			if (get_user(number, &csioc->number))
+				return -EFAULT;
+#endif
+		} else {
+			struct atmif_sioc __user *sioc = argp;
+
+			len = &sioc->length;
+			if (get_user(buf, &sioc->arg))
+				return -EFAULT;
+			if (get_user(number, &sioc->number))
+				return -EFAULT;
+		}
+		error = atm_dev_ioctl(cmd, buf, len, number, compat);
+	}
+
+done:
+	return error;
+}
+
+int vcc_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
+{
+	return do_vcc_ioctl(sock, cmd, arg, 0);
+}
+
+#ifdef CONFIG_COMPAT
+/*
+ * FIXME:
+ * The compat_ioctl handling is duplicated, using both these conversion
+ * routines and the compat argument to the actual handlers. Both
+ * versions are somewhat incomplete and should be merged, e.g. by
+ * moving the ioctl number translation into the actual handlers and
+ * killing the conversion code.
+ *
+ * -arnd, November 2009
+ */
+#define ATM_GETLINKRATE32 _IOW('a', ATMIOC_ITF+1, struct compat_atmif_sioc)
+#define ATM_GETNAMES32    _IOW('a', ATMIOC_ITF+3, struct compat_atm_iobuf)
+#define ATM_GETTYPE32     _IOW('a', ATMIOC_ITF+4, struct compat_atmif_sioc)
+#define ATM_GETESI32	  _IOW('a', ATMIOC_ITF+5, struct compat_atmif_sioc)
+#define ATM_GETCIRANGE32  _IOW('a', ATMIOC_ITF+10, struct compat_atmif_sioc)
+#define ATM_SETCIRANGE32  _IOW('a', ATMIOC_ITF+11, struct compat_atmif_sioc)
+#define ATM_SETESI32      _IOW('a', ATMIOC_ITF+12, struct compat_atmif_sioc)
+#define ATM_SETESIF32     _IOW('a', ATMIOC_ITF+13, struct compat_atmif_sioc)
+#define ATM_GETSTAT32     _IOW('a', ATMIOC_SARCOM+0, struct compat_atmif_sioc)
+#define ATM_GETSTATZ32    _IOW('a', ATMIOC_SARCOM+1, struct compat_atmif_sioc)
+#define ATM_GETLOOP32	  _IOW('a', ATMIOC_SARCOM+2, struct compat_atmif_sioc)
+#define ATM_SETLOOP32	  _IOW('a', ATMIOC_SARCOM+3, struct compat_atmif_sioc)
+#define ATM_QUERYLOOP32	  _IOW('a', ATMIOC_SARCOM+4, struct compat_atmif_sioc)
+
+static struct {
+	unsigned int cmd32;
+	unsigned int cmd;
+} atm_ioctl_map[] = {
+	{ ATM_GETLINKRATE32, ATM_GETLINKRATE },
+	{ ATM_GETNAMES32,    ATM_GETNAMES },
+	{ ATM_GETTYPE32,     ATM_GETTYPE },
+	{ ATM_GETESI32,	     ATM_GETESI },
+	{ ATM_GETCIRANGE32,  ATM_GETCIRANGE },
+	{ ATM_SETCIRANGE32,  ATM_SETCIRANGE },
+	{ ATM_SETESI32,	     ATM_SETESI },
+	{ ATM_SETESIF32,     ATM_SETESIF },
+	{ ATM_GETSTAT32,     ATM_GETSTAT },
+	{ ATM_GETSTATZ32,    ATM_GETSTATZ },
+	{ ATM_GETLOOP32,     ATM_GETLOOP },
+	{ ATM_SETLOOP32,     ATM_SETLOOP },
+	{ ATM_QUERYLOOP32,   ATM_QUERYLOOP },
+};
+
+#define NR_ATM_IOCTL ARRAY_SIZE(atm_ioctl_map)
+
+static int do_atm_iobuf(struct socket *sock, unsigned int cmd,
+			unsigned long arg)
+{
+	struct compat_atm_iobuf __user *iobuf32 = compat_ptr(arg);
+	u32 data;
+
+	if (get_user(data, &iobuf32->buffer))
+		return -EFAULT;
+
+	return atm_getnames(&iobuf32->length, compat_ptr(data));
+}
+
+static int do_atmif_sioc(struct socket *sock, unsigned int cmd,
+			 unsigned long arg)
+{
+	struct compat_atmif_sioc __user *sioc32 = compat_ptr(arg);
+	int number;
+	u32 data;
+
+	if (get_user(data, &sioc32->arg) || get_user(number, &sioc32->number))
+		return -EFAULT;
+	return atm_dev_ioctl(cmd, compat_ptr(data), &sioc32->length, number, 0);
+}
+
+static int do_atm_ioctl(struct socket *sock, unsigned int cmd32,
+			unsigned long arg)
+{
+	int i;
+	unsigned int cmd = 0;
+
+	for (i = 0; i < NR_ATM_IOCTL; i++) {
+		if (cmd32 == atm_ioctl_map[i].cmd32) {
+			cmd = atm_ioctl_map[i].cmd;
+			break;
+		}
+	}
+	if (i == NR_ATM_IOCTL)
+		return -EINVAL;
+
+	switch (cmd) {
+	case ATM_GETNAMES:
+		return do_atm_iobuf(sock, cmd, arg);
+
+	case ATM_GETLINKRATE:
+	case ATM_GETTYPE:
+	case ATM_GETESI:
+	case ATM_GETCIRANGE:
+	case ATM_SETCIRANGE:
+	case ATM_SETESI:
+	case ATM_SETESIF:
+	case ATM_GETSTAT:
+	case ATM_GETSTATZ:
+	case ATM_GETLOOP:
+	case ATM_SETLOOP:
+	case ATM_QUERYLOOP:
+		return do_atmif_sioc(sock, cmd, arg);
+	}
+
+	return -EINVAL;
+}
+
+int vcc_compat_ioctl(struct socket *sock, unsigned int cmd,
+		     unsigned long arg)
+{
+	int ret;
+
+	ret = do_vcc_ioctl(sock, cmd, arg, 1);
+	if (ret != -ENOIOCTLCMD)
+		return ret;
+
+	return do_atm_ioctl(sock, cmd, arg);
+}
+#endif