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, 111 insertions, 0 deletions

diff --git a/lib/crypto/tests/test-utils.h b/lib/crypto/tests/test-utils.h
new file mode 100644
index 000000000..73ca21f91
--- /dev/null
+++ b/lib/crypto/tests/test-utils.h
@@ -0,0 +1,111 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Test utility functions shared by the crypto library tests.
+ *
+ * For now this is simply a header that's included into the KUnit test suites
+ * that need it.  If this gets too large it could be made its own translation
+ * unit and libcrypto_test_utils module, but that seems overkill for now.
+ */
+#ifndef LIB_CRYPTO_TEST_UTILS_H
+#define LIB_CRYPTO_TEST_UTILS_H
+
+#include <kunit/test.h>
+#include <linux/math.h>
+#include <linux/minmax.h>
+#include <linux/string.h>
+#include <linux/vmalloc.h>
+
+static u64 random_seed;
+
+static __maybe_unused void action_free_guarded_buf(void *buf)
+{
+	vfree(buf);
+}
+
+/*
+ * Allocate a KUnit-managed buffer that has length @size bytes (> 0) immediately
+ * followed by an unmapped page, and assert that the allocation succeeds.
+ */
+static __maybe_unused void *alloc_guarded_buf(struct kunit *test, size_t size)
+{
+	size_t full_size = round_up(size, PAGE_SIZE);
+	void *buf = vmalloc(full_size);
+
+	KUNIT_ASSERT_NOT_NULL(test, buf);
+	KUNIT_ASSERT_EQ(test, 0,
+			kunit_add_action_or_reset(test, action_free_guarded_buf,
+						  buf));
+	return buf + full_size - size;
+}
+
+static __maybe_unused void *alloc_buf(struct kunit *test, size_t size)
+{
+	void *buf = kunit_kmalloc(test, size, GFP_KERNEL);
+
+	KUNIT_ASSERT_NOT_NULL(test, buf);
+	return buf;
+}
+
+static __maybe_unused void *memdup_buf(struct kunit *test, const void *src,
+				       size_t size)
+{
+	void *dst = alloc_buf(test, size);
+
+	return memcpy(dst, src, size);
+}
+
+/*
+ * This is a simple linear congruential generator.  It is used only for testing,
+ * which does not require cryptographically secure random numbers.  A hard-coded
+ * algorithm is used instead of <linux/prandom.h> so that it matches the
+ * algorithm used by the test vector generation script.  This allows the input
+ * data in random test vectors to be concisely stored as just the seed.
+ */
+static __maybe_unused u32 rand32(void)
+{
+	random_seed = (random_seed * 25214903917 + 11) & ((1ULL << 48) - 1);
+	return random_seed >> 16;
+}
+
+static __maybe_unused void rand_bytes(u8 *out, size_t len)
+{
+	for (size_t i = 0; i < len; i++)
+		out[i] = rand32();
+}
+
+static __maybe_unused void rand_bytes_seeded_from_len(u8 *out, size_t len)
+{
+	random_seed = len;
+	rand_bytes(out, len);
+}
+
+static __maybe_unused bool rand_bool(void)
+{
+	return rand32() % 2;
+}
+
+/* Generate a random length, preferring small lengths. */
+static __maybe_unused size_t rand_length(size_t max_len)
+{
+	size_t len;
+
+	switch (rand32() % 3) {
+	case 0:
+		len = rand32() % 128;
+		break;
+	case 1:
+		len = rand32() % 3072;
+		break;
+	default:
+		len = rand32();
+		break;
+	}
+	return len % (max_len + 1);
+}
+
+static __maybe_unused size_t rand_offset(size_t max_offset)
+{
+	return min(rand32() % 128, max_offset);
+}
+
+#endif /* LIB_CRYPTO_TEST_UTILS_H */