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, 129 insertions, 0 deletions

diff --git a/crypto/crc32.c b/crypto/crc32.c
new file mode 100644
index 000000000..489cbed94
--- /dev/null
+++ b/crypto/crc32.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2012 Xyratex Technology Limited
+ */
+
+/*
+ * This is crypto api shash wrappers to crc32_le.
+ */
+
+#include <linux/unaligned.h>
+#include <linux/crc32.h>
+#include <crypto/internal/hash.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+
+#define CHKSUM_BLOCK_SIZE	1
+#define CHKSUM_DIGEST_SIZE	4
+
+/** No default init with ~0 */
+static int crc32_cra_init(struct crypto_tfm *tfm)
+{
+	u32 *key = crypto_tfm_ctx(tfm);
+
+	*key = 0;
+
+	return 0;
+}
+
+/*
+ * Setting the seed allows arbitrary accumulators and flexible XOR policy
+ * If your algorithm starts with ~0, then XOR with ~0 before you set
+ * the seed.
+ */
+static int crc32_setkey(struct crypto_shash *hash, const u8 *key,
+			unsigned int keylen)
+{
+	u32 *mctx = crypto_shash_ctx(hash);
+
+	if (keylen != sizeof(u32))
+		return -EINVAL;
+	*mctx = get_unaligned_le32(key);
+	return 0;
+}
+
+static int crc32_init(struct shash_desc *desc)
+{
+	u32 *mctx = crypto_shash_ctx(desc->tfm);
+	u32 *crcp = shash_desc_ctx(desc);
+
+	*crcp = *mctx;
+
+	return 0;
+}
+
+static int crc32_update(struct shash_desc *desc, const u8 *data,
+			unsigned int len)
+{
+	u32 *crcp = shash_desc_ctx(desc);
+
+	*crcp = crc32_le(*crcp, data, len);
+	return 0;
+}
+
+/* No final XOR 0xFFFFFFFF, like crc32_le */
+static int __crc32_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out)
+{
+	put_unaligned_le32(crc32_le(*crcp, data, len), out);
+	return 0;
+}
+
+static int crc32_finup(struct shash_desc *desc, const u8 *data,
+		       unsigned int len, u8 *out)
+{
+	return __crc32_finup(shash_desc_ctx(desc), data, len, out);
+}
+
+static int crc32_final(struct shash_desc *desc, u8 *out)
+{
+	u32 *crcp = shash_desc_ctx(desc);
+
+	put_unaligned_le32(*crcp, out);
+	return 0;
+}
+
+static int crc32_digest(struct shash_desc *desc, const u8 *data,
+			unsigned int len, u8 *out)
+{
+	return __crc32_finup(crypto_shash_ctx(desc->tfm), data, len, out);
+}
+
+static struct shash_alg alg = {
+	.setkey			= crc32_setkey,
+	.init			= crc32_init,
+	.update			= crc32_update,
+	.final			= crc32_final,
+	.finup			= crc32_finup,
+	.digest			= crc32_digest,
+	.descsize		= sizeof(u32),
+	.digestsize		= CHKSUM_DIGEST_SIZE,
+
+	.base.cra_name		= "crc32",
+	.base.cra_driver_name	= "crc32-lib",
+	.base.cra_priority	= 100,
+	.base.cra_flags		= CRYPTO_ALG_OPTIONAL_KEY,
+	.base.cra_blocksize	= CHKSUM_BLOCK_SIZE,
+	.base.cra_ctxsize	= sizeof(u32),
+	.base.cra_module	= THIS_MODULE,
+	.base.cra_init		= crc32_cra_init,
+};
+
+static int __init crc32_mod_init(void)
+{
+	return crypto_register_shash(&alg);
+}
+
+static void __exit crc32_mod_fini(void)
+{
+	crypto_unregister_shash(&alg);
+}
+
+module_init(crc32_mod_init);
+module_exit(crc32_mod_fini);
+
+MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
+MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_CRYPTO("crc32");