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, 236 insertions, 0 deletions

diff --git a/crypto/md5.c b/crypto/md5.c
new file mode 100644
index 000000000..c167d203c
--- /dev/null
+++ b/crypto/md5.c
@@ -0,0 +1,236 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Crypto API support for MD5 and HMAC-MD5
+ *
+ * Copyright 2025 Google LLC
+ */
+#include <crypto/internal/hash.h>
+#include <crypto/md5.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+/*
+ * Export and import functions.  crypto_shash wants a particular format that
+ * matches that used by some legacy drivers.  It currently is the same as the
+ * library MD5 context, except the value in bytecount must be block-aligned and
+ * the remainder must be stored in an extra u8 appended to the struct.
+ */
+
+#define MD5_SHASH_STATE_SIZE (sizeof(struct md5_ctx) + 1)
+static_assert(sizeof(struct md5_ctx) == sizeof(struct md5_state));
+static_assert(offsetof(struct md5_ctx, state) == offsetof(struct md5_state, hash));
+static_assert(offsetof(struct md5_ctx, bytecount) == offsetof(struct md5_state, byte_count));
+static_assert(offsetof(struct md5_ctx, buf) == offsetof(struct md5_state, block));
+
+static int __crypto_md5_export(const struct md5_ctx *ctx0, void *out)
+{
+	struct md5_ctx ctx = *ctx0;
+	unsigned int partial;
+	u8 *p = out;
+
+	partial = ctx.bytecount % MD5_BLOCK_SIZE;
+	ctx.bytecount -= partial;
+	memcpy(p, &ctx, sizeof(ctx));
+	p += sizeof(ctx);
+	*p = partial;
+	return 0;
+}
+
+static int __crypto_md5_import(struct md5_ctx *ctx, const void *in)
+{
+	const u8 *p = in;
+
+	memcpy(ctx, p, sizeof(*ctx));
+	p += sizeof(*ctx);
+	ctx->bytecount += *p;
+	return 0;
+}
+
+static int __crypto_md5_export_core(const struct md5_ctx *ctx, void *out)
+{
+	memcpy(out, ctx, offsetof(struct md5_ctx, buf));
+	return 0;
+}
+
+static int __crypto_md5_import_core(struct md5_ctx *ctx, const void *in)
+{
+	memcpy(ctx, in, offsetof(struct md5_ctx, buf));
+	return 0;
+}
+
+const u8 md5_zero_message_hash[MD5_DIGEST_SIZE] = {
+	0xd4, 0x1d, 0x8c, 0xd9, 0x8f, 0x00, 0xb2, 0x04,
+	0xe9, 0x80, 0x09, 0x98, 0xec, 0xf8, 0x42, 0x7e,
+};
+EXPORT_SYMBOL_GPL(md5_zero_message_hash);
+
+#define MD5_CTX(desc) ((struct md5_ctx *)shash_desc_ctx(desc))
+
+static int crypto_md5_init(struct shash_desc *desc)
+{
+	md5_init(MD5_CTX(desc));
+	return 0;
+}
+
+static int crypto_md5_update(struct shash_desc *desc,
+			     const u8 *data, unsigned int len)
+{
+	md5_update(MD5_CTX(desc), data, len);
+	return 0;
+}
+
+static int crypto_md5_final(struct shash_desc *desc, u8 *out)
+{
+	md5_final(MD5_CTX(desc), out);
+	return 0;
+}
+
+static int crypto_md5_digest(struct shash_desc *desc,
+			     const u8 *data, unsigned int len, u8 *out)
+{
+	md5(data, len, out);
+	return 0;
+}
+
+static int crypto_md5_export(struct shash_desc *desc, void *out)
+{
+	return __crypto_md5_export(MD5_CTX(desc), out);
+}
+
+static int crypto_md5_import(struct shash_desc *desc, const void *in)
+{
+	return __crypto_md5_import(MD5_CTX(desc), in);
+}
+
+static int crypto_md5_export_core(struct shash_desc *desc, void *out)
+{
+	return __crypto_md5_export_core(MD5_CTX(desc), out);
+}
+
+static int crypto_md5_import_core(struct shash_desc *desc, const void *in)
+{
+	return __crypto_md5_import_core(MD5_CTX(desc), in);
+}
+
+#define HMAC_MD5_KEY(tfm) ((struct hmac_md5_key *)crypto_shash_ctx(tfm))
+#define HMAC_MD5_CTX(desc) ((struct hmac_md5_ctx *)shash_desc_ctx(desc))
+
+static int crypto_hmac_md5_setkey(struct crypto_shash *tfm,
+				  const u8 *raw_key, unsigned int keylen)
+{
+	hmac_md5_preparekey(HMAC_MD5_KEY(tfm), raw_key, keylen);
+	return 0;
+}
+
+static int crypto_hmac_md5_init(struct shash_desc *desc)
+{
+	hmac_md5_init(HMAC_MD5_CTX(desc), HMAC_MD5_KEY(desc->tfm));
+	return 0;
+}
+
+static int crypto_hmac_md5_update(struct shash_desc *desc,
+				  const u8 *data, unsigned int len)
+{
+	hmac_md5_update(HMAC_MD5_CTX(desc), data, len);
+	return 0;
+}
+
+static int crypto_hmac_md5_final(struct shash_desc *desc, u8 *out)
+{
+	hmac_md5_final(HMAC_MD5_CTX(desc), out);
+	return 0;
+}
+
+static int crypto_hmac_md5_digest(struct shash_desc *desc,
+				  const u8 *data, unsigned int len, u8 *out)
+{
+	hmac_md5(HMAC_MD5_KEY(desc->tfm), data, len, out);
+	return 0;
+}
+
+static int crypto_hmac_md5_export(struct shash_desc *desc, void *out)
+{
+	return __crypto_md5_export(&HMAC_MD5_CTX(desc)->hash_ctx, out);
+}
+
+static int crypto_hmac_md5_import(struct shash_desc *desc, const void *in)
+{
+	struct hmac_md5_ctx *ctx = HMAC_MD5_CTX(desc);
+
+	ctx->ostate = HMAC_MD5_KEY(desc->tfm)->ostate;
+	return __crypto_md5_import(&ctx->hash_ctx, in);
+}
+
+static int crypto_hmac_md5_export_core(struct shash_desc *desc, void *out)
+{
+	return __crypto_md5_export_core(&HMAC_MD5_CTX(desc)->hash_ctx, out);
+}
+
+static int crypto_hmac_md5_import_core(struct shash_desc *desc, const void *in)
+{
+	struct hmac_md5_ctx *ctx = HMAC_MD5_CTX(desc);
+
+	ctx->ostate = HMAC_MD5_KEY(desc->tfm)->ostate;
+	return __crypto_md5_import_core(&ctx->hash_ctx, in);
+}
+
+static struct shash_alg algs[] = {
+	{
+		.base.cra_name		= "md5",
+		.base.cra_driver_name	= "md5-lib",
+		.base.cra_priority	= 300,
+		.base.cra_blocksize	= MD5_BLOCK_SIZE,
+		.base.cra_module	= THIS_MODULE,
+		.digestsize		= MD5_DIGEST_SIZE,
+		.init			= crypto_md5_init,
+		.update			= crypto_md5_update,
+		.final			= crypto_md5_final,
+		.digest			= crypto_md5_digest,
+		.export			= crypto_md5_export,
+		.import			= crypto_md5_import,
+		.export_core		= crypto_md5_export_core,
+		.import_core		= crypto_md5_import_core,
+		.descsize		= sizeof(struct md5_ctx),
+		.statesize		= MD5_SHASH_STATE_SIZE,
+	},
+	{
+		.base.cra_name		= "hmac(md5)",
+		.base.cra_driver_name	= "hmac-md5-lib",
+		.base.cra_priority	= 300,
+		.base.cra_blocksize	= MD5_BLOCK_SIZE,
+		.base.cra_ctxsize	= sizeof(struct hmac_md5_key),
+		.base.cra_module	= THIS_MODULE,
+		.digestsize		= MD5_DIGEST_SIZE,
+		.setkey			= crypto_hmac_md5_setkey,
+		.init			= crypto_hmac_md5_init,
+		.update			= crypto_hmac_md5_update,
+		.final			= crypto_hmac_md5_final,
+		.digest			= crypto_hmac_md5_digest,
+		.export			= crypto_hmac_md5_export,
+		.import			= crypto_hmac_md5_import,
+		.export_core		= crypto_hmac_md5_export_core,
+		.import_core		= crypto_hmac_md5_import_core,
+		.descsize		= sizeof(struct hmac_md5_ctx),
+		.statesize		= MD5_SHASH_STATE_SIZE,
+	},
+};
+
+static int __init crypto_md5_mod_init(void)
+{
+	return crypto_register_shashes(algs, ARRAY_SIZE(algs));
+}
+module_init(crypto_md5_mod_init);
+
+static void __exit crypto_md5_mod_exit(void)
+{
+	crypto_unregister_shashes(algs, ARRAY_SIZE(algs));
+}
+module_exit(crypto_md5_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Crypto API support for MD5 and HMAC-MD5");
+
+MODULE_ALIAS_CRYPTO("md5");
+MODULE_ALIAS_CRYPTO("md5-lib");
+MODULE_ALIAS_CRYPTO("hmac(md5)");
+MODULE_ALIAS_CRYPTO("hmac-md5-lib");