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/crypto/rng.c b/crypto/rng.c
new file mode 100644
index 000000000..828b0d807
--- /dev/null
+++ b/crypto/rng.c
@@ -0,0 +1,245 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Cryptographic API.
+ *
+ * RNG operations.
+ *
+ * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
+ * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <crypto/internal/rng.h>
+#include <linux/atomic.h>
+#include <linux/cryptouser.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/random.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <net/netlink.h>
+
+#include "internal.h"
+
+static DEFINE_MUTEX(crypto_default_rng_lock);
+static struct crypto_rng *crypto_default_rng;
+static int crypto_default_rng_refcnt;
+
+int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
+{
+	u8 *buf = NULL;
+	int err;
+
+	if (!seed && slen) {
+		buf = kmalloc(slen, GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+
+		err = get_random_bytes_wait(buf, slen);
+		if (err)
+			goto out;
+		seed = buf;
+	}
+
+	err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
+out:
+	kfree_sensitive(buf);
+	return err;
+}
+EXPORT_SYMBOL_GPL(crypto_rng_reset);
+
+static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
+{
+	return 0;
+}
+
+static unsigned int seedsize(struct crypto_alg *alg)
+{
+	struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
+
+	return ralg->seedsize;
+}
+
+static int __maybe_unused crypto_rng_report(
+	struct sk_buff *skb, struct crypto_alg *alg)
+{
+	struct crypto_report_rng rrng = {
+		.type = "rng",
+	};
+
+	rrng.seedsize = seedsize(alg);
+
+	return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng);
+}
+
+static void __maybe_unused crypto_rng_show(struct seq_file *m,
+					   struct crypto_alg *alg)
+{
+	seq_printf(m, "type         : rng\n");
+	seq_printf(m, "seedsize     : %u\n", seedsize(alg));
+}
+
+static const struct crypto_type crypto_rng_type = {
+	.extsize = crypto_alg_extsize,
+	.init_tfm = crypto_rng_init_tfm,
+#ifdef CONFIG_PROC_FS
+	.show = crypto_rng_show,
+#endif
+#if IS_ENABLED(CONFIG_CRYPTO_USER)
+	.report = crypto_rng_report,
+#endif
+	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
+	.maskset = CRYPTO_ALG_TYPE_MASK,
+	.type = CRYPTO_ALG_TYPE_RNG,
+	.tfmsize = offsetof(struct crypto_rng, base),
+	.algsize = offsetof(struct rng_alg, base),
+};
+
+struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
+{
+	return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_rng);
+
+static int crypto_get_default_rng(void)
+{
+	struct crypto_rng *rng;
+	int err;
+
+	mutex_lock(&crypto_default_rng_lock);
+	if (!crypto_default_rng) {
+		rng = crypto_alloc_rng("stdrng", 0, 0);
+		err = PTR_ERR(rng);
+		if (IS_ERR(rng))
+			goto unlock;
+
+		err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
+		if (err) {
+			crypto_free_rng(rng);
+			goto unlock;
+		}
+
+		crypto_default_rng = rng;
+	}
+
+	crypto_default_rng_refcnt++;
+	err = 0;
+
+unlock:
+	mutex_unlock(&crypto_default_rng_lock);
+
+	return err;
+}
+
+static void crypto_put_default_rng(void)
+{
+	mutex_lock(&crypto_default_rng_lock);
+	crypto_default_rng_refcnt--;
+	mutex_unlock(&crypto_default_rng_lock);
+}
+
+int __crypto_stdrng_get_bytes(void *buf, unsigned int len)
+{
+	int err;
+
+	err = crypto_get_default_rng();
+	if (err)
+		return err;
+
+	err = crypto_rng_get_bytes(crypto_default_rng, buf, len);
+	crypto_put_default_rng();
+	return err;
+}
+EXPORT_SYMBOL_GPL(__crypto_stdrng_get_bytes);
+
+#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
+int crypto_del_default_rng(void)
+{
+	int err = -EBUSY;
+
+	mutex_lock(&crypto_default_rng_lock);
+	if (crypto_default_rng_refcnt)
+		goto out;
+
+	crypto_free_rng(crypto_default_rng);
+	crypto_default_rng = NULL;
+
+	err = 0;
+
+out:
+	mutex_unlock(&crypto_default_rng_lock);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(crypto_del_default_rng);
+#endif
+
+static void rng_default_set_ent(struct crypto_rng *tfm, const u8 *data,
+				unsigned int len)
+{
+}
+
+int crypto_register_rng(struct rng_alg *alg)
+{
+	struct crypto_alg *base = &alg->base;
+
+	if (alg->seedsize > PAGE_SIZE / 8)
+		return -EINVAL;
+
+	base->cra_type = &crypto_rng_type;
+	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
+	base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
+
+	if (!alg->set_ent)
+		alg->set_ent = rng_default_set_ent;
+
+	return crypto_register_alg(base);
+}
+EXPORT_SYMBOL_GPL(crypto_register_rng);
+
+void crypto_unregister_rng(struct rng_alg *alg)
+{
+	crypto_unregister_alg(&alg->base);
+}
+EXPORT_SYMBOL_GPL(crypto_unregister_rng);
+
+int crypto_register_rngs(struct rng_alg *algs, int count)
+{
+	int i, ret;
+
+	for (i = 0; i < count; i++) {
+		ret = crypto_register_rng(algs + i);
+		if (ret) {
+			crypto_unregister_rngs(algs, i);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_register_rngs);
+
+void crypto_unregister_rngs(struct rng_alg *algs, int count)
+{
+	int i;
+
+	for (i = count - 1; i >= 0; --i)
+		crypto_unregister_rng(algs + i);
+}
+EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
+
+static void __exit rng_exit(void)
+{
+	int err;
+
+	err = crypto_del_default_rng();
+	if (err)
+		pr_err("Failed delete default RNG: %d\n", err);
+}
+
+module_exit(rng_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Random Number Generator");