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, 245 insertions, 0 deletions

diff --git a/net/llc/llc_proc.c b/net/llc/llc_proc.c
new file mode 100644
index 000000000..4804a08c2
--- /dev/null
+++ b/net/llc/llc_proc.c
@@ -0,0 +1,245 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * proc_llc.c - proc interface for LLC
+ *
+ * Copyright (c) 2001 by Jay Schulist <jschlst@samba.org>
+ *		 2002-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/proc_fs.h>
+#include <linux/errno.h>
+#include <linux/seq_file.h>
+#include <linux/export.h>
+#include <net/net_namespace.h>
+#include <net/sock.h>
+#include <net/llc.h>
+#include <net/llc_c_ac.h>
+#include <net/llc_c_ev.h>
+#include <net/llc_c_st.h>
+#include <net/llc_conn.h>
+
+static void llc_ui_format_mac(struct seq_file *seq, const u8 *addr)
+{
+	seq_printf(seq, "%pM", addr);
+}
+
+static struct sock *llc_get_sk_idx(loff_t pos)
+{
+	struct llc_sap *sap;
+	struct sock *sk = NULL;
+	int i;
+
+	list_for_each_entry_rcu(sap, &llc_sap_list, node) {
+		spin_lock_bh(&sap->sk_lock);
+		for (i = 0; i < LLC_SK_LADDR_HASH_ENTRIES; i++) {
+			struct hlist_nulls_head *head = &sap->sk_laddr_hash[i];
+			struct hlist_nulls_node *node;
+
+			sk_nulls_for_each(sk, node, head) {
+				if (!pos)
+					goto found; /* keep the lock */
+				--pos;
+			}
+		}
+		spin_unlock_bh(&sap->sk_lock);
+	}
+	sk = NULL;
+found:
+	return sk;
+}
+
+static void *llc_seq_start(struct seq_file *seq, loff_t *pos) __acquires(RCU)
+{
+	loff_t l = *pos;
+
+	rcu_read_lock_bh();
+	return l ? llc_get_sk_idx(--l) : SEQ_START_TOKEN;
+}
+
+static struct sock *laddr_hash_next(struct llc_sap *sap, int bucket)
+{
+	struct hlist_nulls_node *node;
+	struct sock *sk = NULL;
+
+	while (++bucket < LLC_SK_LADDR_HASH_ENTRIES)
+		sk_nulls_for_each(sk, node, &sap->sk_laddr_hash[bucket])
+			goto out;
+
+out:
+	return sk;
+}
+
+static void *llc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct sock* sk, *next;
+	struct llc_sock *llc;
+	struct llc_sap *sap;
+
+	++*pos;
+	if (v == SEQ_START_TOKEN) {
+		sk = llc_get_sk_idx(0);
+		goto out;
+	}
+	sk = v;
+	next = sk_nulls_next(sk);
+	if (next) {
+		sk = next;
+		goto out;
+	}
+	llc = llc_sk(sk);
+	sap = llc->sap;
+	sk = laddr_hash_next(sap, llc_sk_laddr_hashfn(sap, &llc->laddr));
+	if (sk)
+		goto out;
+	spin_unlock_bh(&sap->sk_lock);
+	list_for_each_entry_continue_rcu(sap, &llc_sap_list, node) {
+		spin_lock_bh(&sap->sk_lock);
+		sk = laddr_hash_next(sap, -1);
+		if (sk)
+			break; /* keep the lock */
+		spin_unlock_bh(&sap->sk_lock);
+	}
+out:
+	return sk;
+}
+
+static void llc_seq_stop(struct seq_file *seq, void *v)
+{
+	if (v && v != SEQ_START_TOKEN) {
+		struct sock *sk = v;
+		struct llc_sock *llc = llc_sk(sk);
+		struct llc_sap *sap = llc->sap;
+
+		spin_unlock_bh(&sap->sk_lock);
+	}
+	rcu_read_unlock_bh();
+}
+
+static int llc_seq_socket_show(struct seq_file *seq, void *v)
+{
+	struct sock* sk;
+	struct llc_sock *llc;
+
+	if (v == SEQ_START_TOKEN) {
+		seq_puts(seq, "SKt Mc local_mac_sap        remote_mac_sap   "
+			      "    tx_queue rx_queue st uid link\n");
+		goto out;
+	}
+	sk = v;
+	llc = llc_sk(sk);
+
+	/* FIXME: check if the address is multicast */
+	seq_printf(seq, "%2X  %2X ", sk->sk_type, 0);
+
+	if (llc->dev)
+		llc_ui_format_mac(seq, llc->dev->dev_addr);
+	else {
+		u8 addr[6] = {0,0,0,0,0,0};
+		llc_ui_format_mac(seq, addr);
+	}
+	seq_printf(seq, "@%02X ", llc->sap->laddr.lsap);
+	llc_ui_format_mac(seq, llc->daddr.mac);
+	seq_printf(seq, "@%02X %8d %8d %2d %3u %4d\n", llc->daddr.lsap,
+		   sk_wmem_alloc_get(sk),
+		   sk_rmem_alloc_get(sk) - llc->copied_seq,
+		   sk->sk_state,
+		   from_kuid_munged(seq_user_ns(seq), sk_uid(sk)),
+		   llc->link);
+out:
+	return 0;
+}
+
+static const char *const llc_conn_state_names[] = {
+	[LLC_CONN_STATE_ADM] =        "adm",
+	[LLC_CONN_STATE_SETUP] =      "setup",
+	[LLC_CONN_STATE_NORMAL] =     "normal",
+	[LLC_CONN_STATE_BUSY] =       "busy",
+	[LLC_CONN_STATE_REJ] =        "rej",
+	[LLC_CONN_STATE_AWAIT] =      "await",
+	[LLC_CONN_STATE_AWAIT_BUSY] = "await_busy",
+	[LLC_CONN_STATE_AWAIT_REJ] =  "await_rej",
+	[LLC_CONN_STATE_D_CONN]	=     "d_conn",
+	[LLC_CONN_STATE_RESET] =      "reset",
+	[LLC_CONN_STATE_ERROR] =      "error",
+	[LLC_CONN_STATE_TEMP] =       "temp",
+};
+
+static int llc_seq_core_show(struct seq_file *seq, void *v)
+{
+	struct sock* sk;
+	struct llc_sock *llc;
+
+	if (v == SEQ_START_TOKEN) {
+		seq_puts(seq, "Connection list:\n"
+			      "dsap state      retr txw rxw pf ff sf df rs cs "
+			      "tack tpfc trs tbs blog busr\n");
+		goto out;
+	}
+	sk = v;
+	llc = llc_sk(sk);
+
+	seq_printf(seq, " %02X  %-10s %3d  %3d %3d %2d %2d %2d %2d %2d %2d "
+			"%4d %4d %3d %3d %4d %4d\n",
+		   llc->daddr.lsap, llc_conn_state_names[llc->state],
+		   llc->retry_count, llc->k, llc->rw, llc->p_flag, llc->f_flag,
+		   llc->s_flag, llc->data_flag, llc->remote_busy_flag,
+		   llc->cause_flag, timer_pending(&llc->ack_timer.timer),
+		   timer_pending(&llc->pf_cycle_timer.timer),
+		   timer_pending(&llc->rej_sent_timer.timer),
+		   timer_pending(&llc->busy_state_timer.timer),
+		   !!sk->sk_backlog.tail, sock_owned_by_user_nocheck(sk));
+out:
+	return 0;
+}
+
+static const struct seq_operations llc_seq_socket_ops = {
+	.start  = llc_seq_start,
+	.next   = llc_seq_next,
+	.stop   = llc_seq_stop,
+	.show   = llc_seq_socket_show,
+};
+
+static const struct seq_operations llc_seq_core_ops = {
+	.start  = llc_seq_start,
+	.next   = llc_seq_next,
+	.stop   = llc_seq_stop,
+	.show   = llc_seq_core_show,
+};
+
+static struct proc_dir_entry *llc_proc_dir;
+
+int __init llc_proc_init(void)
+{
+	int rc = -ENOMEM;
+	struct proc_dir_entry *p;
+
+	llc_proc_dir = proc_mkdir("llc", init_net.proc_net);
+	if (!llc_proc_dir)
+		goto out;
+
+	p = proc_create_seq("socket", 0444, llc_proc_dir, &llc_seq_socket_ops);
+	if (!p)
+		goto out_socket;
+
+	p = proc_create_seq("core", 0444, llc_proc_dir, &llc_seq_core_ops);
+	if (!p)
+		goto out_core;
+
+	rc = 0;
+out:
+	return rc;
+out_core:
+	remove_proc_entry("socket", llc_proc_dir);
+out_socket:
+	remove_proc_entry("llc", init_net.proc_net);
+	goto out;
+}
+
+void llc_proc_exit(void)
+{
+	remove_proc_entry("socket", llc_proc_dir);
+	remove_proc_entry("core", llc_proc_dir);
+	remove_proc_entry("llc", init_net.proc_net);
+}