Merge tag 'hardening-v6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening updates from Kees Cook:

 - Introduce and start using TRAILING_OVERLAP() helper for fixing
   embedded flex array instances (Gustavo A. R. Silva)

 - mux: Convert mux_control_ops to a flex array member in mux_chip
   (Thorsten Blum)

 - string: Group str_has_prefix() and strstarts() (Andy Shevchenko)

 - Remove KCOV instrumentation from __init and __head (Ritesh Harjani,
   Kees Cook)

 - Refactor and rename stackleak feature to support Clang

 - Add KUnit test for seq_buf API

 - Fix KUnit fortify test under LTO

* tag 'hardening-v6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (22 commits)
  sched/task_stack: Add missing const qualifier to end_of_stack()
  kstack_erase: Support Clang stack depth tracking
  kstack_erase: Add -mgeneral-regs-only to silence Clang warnings
  init.h: Disable sanitizer coverage for __init and __head
  kstack_erase: Disable kstack_erase for all of arm compressed boot code
  x86: Handle KCOV __init vs inline mismatches
  arm64: Handle KCOV __init vs inline mismatches
  s390: Handle KCOV __init vs inline mismatches
  arm: Handle KCOV __init vs inline mismatches
  mips: Handle KCOV __init vs inline mismatch
  powerpc/mm/book3s64: Move kfence and debug_pagealloc related calls to __init section
  configs/hardening: Enable CONFIG_INIT_ON_FREE_DEFAULT_ON
  configs/hardening: Enable CONFIG_KSTACK_ERASE
  stackleak: Split KSTACK_ERASE_CFLAGS from GCC_PLUGINS_CFLAGS
  stackleak: Rename stackleak_track_stack to __sanitizer_cov_stack_depth
  stackleak: Rename STACKLEAK to KSTACK_ERASE
  seq_buf: Introduce KUnit tests
  string: Group str_has_prefix() and strstarts()
  kunit/fortify: Add back "volatile" for sizeof() constants
  acpi: nfit: intel: avoid multiple -Wflex-array-member-not-at-end warnings
  ...

5 files changed, 221 insertions, 3 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ebe33181b6e6..087beae1e8fb 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2460,6 +2460,15 @@ config SCANF_KUNIT_TEST
 
 	  If unsure, say N.
 
+config SEQ_BUF_KUNIT_TEST
+	tristate "KUnit test for seq_buf" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds unit tests for the seq_buf library.
+
+	  If unsure, say N.
+
 config STRING_KUNIT_TEST
 	tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
 	depends on KUNIT
diff --git a/lib/Makefile b/lib/Makefile
index c38582f187dd..632e69d25feb 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -337,7 +337,7 @@ obj-$(CONFIG_UBSAN) += ubsan.o
 UBSAN_SANITIZE_ubsan.o := n
 KASAN_SANITIZE_ubsan.o := n
 KCSAN_SANITIZE_ubsan.o := n
-CFLAGS_ubsan.o := -fno-stack-protector $(DISABLE_STACKLEAK_PLUGIN)
+CFLAGS_ubsan.o := -fno-stack-protector $(DISABLE_KSTACK_ERASE)
 
 obj-$(CONFIG_SBITMAP) += sbitmap.o
 
diff --git a/lib/tests/Makefile b/lib/tests/Makefile
index 56d645014482..8294abbe21f1 100644
--- a/lib/tests/Makefile
+++ b/lib/tests/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += overflow_kunit.o
 obj-$(CONFIG_PRINTF_KUNIT_TEST) += printf_kunit.o
 obj-$(CONFIG_RANDSTRUCT_KUNIT_TEST) += randstruct_kunit.o
 obj-$(CONFIG_SCANF_KUNIT_TEST) += scanf_kunit.o
+obj-$(CONFIG_SEQ_BUF_KUNIT_TEST) += seq_buf_kunit.o
 obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o
 obj-$(CONFIG_SLUB_KUNIT_TEST) += slub_kunit.o
 obj-$(CONFIG_TEST_SORT) += test_sort.o
diff --git a/lib/tests/fortify_kunit.c b/lib/tests/fortify_kunit.c
index 29ffc62a71e3..fc9c76f026d6 100644
--- a/lib/tests/fortify_kunit.c
+++ b/lib/tests/fortify_kunit.c
@@ -1003,8 +1003,8 @@ static void fortify_test_memcmp(struct kunit *test)
 {
 	char one[] = "My mind is going ...";
 	char two[] = "My mind is going ... I can feel it.";
-	size_t one_len = sizeof(one) - 1;
-	size_t two_len = sizeof(two) - 1;
+	volatile size_t one_len = sizeof(one) - 1;
+	volatile size_t two_len = sizeof(two) - 1;
 
 	OPTIMIZER_HIDE_VAR(one_len);
 	OPTIMIZER_HIDE_VAR(two_len);
diff --git a/lib/tests/seq_buf_kunit.c b/lib/tests/seq_buf_kunit.c
new file mode 100644
index 000000000000..8a01579a978e
--- /dev/null
+++ b/lib/tests/seq_buf_kunit.c
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit tests for the seq_buf API
+ *
+ * Copyright (C) 2025, Google LLC.
+ */
+
+#include <kunit/test.h>
+#include <linux/seq_buf.h>
+
+static void seq_buf_init_test(struct kunit *test)
+{
+	char buf[32];
+	struct seq_buf s;
+
+	seq_buf_init(&s, buf, sizeof(buf));
+
+	KUNIT_EXPECT_EQ(test, s.size, 32);
+	KUNIT_EXPECT_EQ(test, s.len, 0);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_EQ(test, seq_buf_buffer_left(&s), 32);
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 0);
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "");
+}
+
+static void seq_buf_declare_test(struct kunit *test)
+{
+	DECLARE_SEQ_BUF(s, 24);
+
+	KUNIT_EXPECT_EQ(test, s.size, 24);
+	KUNIT_EXPECT_EQ(test, s.len, 0);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_EQ(test, seq_buf_buffer_left(&s), 24);
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 0);
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "");
+}
+
+static void seq_buf_clear_test(struct kunit *test)
+{
+	DECLARE_SEQ_BUF(s, 128);
+
+	seq_buf_puts(&s, "hello");
+	KUNIT_EXPECT_EQ(test, s.len, 5);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "hello");
+
+	seq_buf_clear(&s);
+
+	KUNIT_EXPECT_EQ(test, s.len, 0);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "");
+}
+
+static void seq_buf_puts_test(struct kunit *test)
+{
+	DECLARE_SEQ_BUF(s, 16);
+
+	seq_buf_puts(&s, "hello");
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 5);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "hello");
+
+	seq_buf_puts(&s, " world");
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 11);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "hello world");
+}
+
+static void seq_buf_puts_overflow_test(struct kunit *test)
+{
+	DECLARE_SEQ_BUF(s, 10);
+
+	seq_buf_puts(&s, "123456789");
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 9);
+
+	seq_buf_puts(&s, "0");
+	KUNIT_EXPECT_TRUE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 10);
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "123456789");
+
+	seq_buf_clear(&s);
+	KUNIT_EXPECT_EQ(test, s.len, 0);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "");
+}
+
+static void seq_buf_putc_test(struct kunit *test)
+{
+	DECLARE_SEQ_BUF(s, 4);
+
+	seq_buf_putc(&s, 'a');
+	seq_buf_putc(&s, 'b');
+	seq_buf_putc(&s, 'c');
+
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 3);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "abc");
+
+	seq_buf_putc(&s, 'd');
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 4);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "abc");
+
+	seq_buf_putc(&s, 'e');
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 4);
+	KUNIT_EXPECT_TRUE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "abc");
+
+	seq_buf_clear(&s);
+	KUNIT_EXPECT_EQ(test, s.len, 0);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "");
+}
+
+static void seq_buf_printf_test(struct kunit *test)
+{
+	DECLARE_SEQ_BUF(s, 32);
+
+	seq_buf_printf(&s, "hello %s", "world");
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 11);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "hello world");
+
+	seq_buf_printf(&s, " %d", 123);
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 15);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "hello world 123");
+}
+
+static void seq_buf_printf_overflow_test(struct kunit *test)
+{
+	DECLARE_SEQ_BUF(s, 16);
+
+	seq_buf_printf(&s, "%lu", 1234567890UL);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 10);
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "1234567890");
+
+	seq_buf_printf(&s, "%s", "abcdefghij");
+	KUNIT_EXPECT_TRUE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 16);
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "1234567890abcde");
+
+	seq_buf_clear(&s);
+	KUNIT_EXPECT_EQ(test, s.len, 0);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "");
+}
+
+static void seq_buf_get_buf_commit_test(struct kunit *test)
+{
+	DECLARE_SEQ_BUF(s, 16);
+	char *buf;
+	size_t len;
+
+	len = seq_buf_get_buf(&s, &buf);
+	KUNIT_EXPECT_EQ(test, len, 16);
+	KUNIT_EXPECT_PTR_NE(test, buf, NULL);
+
+	memcpy(buf, "hello", 5);
+	seq_buf_commit(&s, 5);
+
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 5);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "hello");
+
+	len = seq_buf_get_buf(&s, &buf);
+	KUNIT_EXPECT_EQ(test, len, 11);
+	KUNIT_EXPECT_PTR_NE(test, buf, NULL);
+
+	memcpy(buf, " worlds!", 8);
+	seq_buf_commit(&s, 6);
+
+	KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 11);
+	KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+	KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), "hello world");
+
+	len = seq_buf_get_buf(&s, &buf);
+	KUNIT_EXPECT_EQ(test, len, 5);
+	KUNIT_EXPECT_PTR_NE(test, buf, NULL);
+
+	seq_buf_commit(&s, -1);
+	KUNIT_EXPECT_TRUE(test, seq_buf_has_overflowed(&s));
+}
+
+static struct kunit_case seq_buf_test_cases[] = {
+	KUNIT_CASE(seq_buf_init_test),
+	KUNIT_CASE(seq_buf_declare_test),
+	KUNIT_CASE(seq_buf_clear_test),
+	KUNIT_CASE(seq_buf_puts_test),
+	KUNIT_CASE(seq_buf_puts_overflow_test),
+	KUNIT_CASE(seq_buf_putc_test),
+	KUNIT_CASE(seq_buf_printf_test),
+	KUNIT_CASE(seq_buf_printf_overflow_test),
+	KUNIT_CASE(seq_buf_get_buf_commit_test),
+	{}
+};
+
+static struct kunit_suite seq_buf_test_suite = {
+	.name = "seq_buf",
+	.test_cases = seq_buf_test_cases,
+};
+
+kunit_test_suite(seq_buf_test_suite);
+
+MODULE_DESCRIPTION("Runtime test cases for seq_buf string API");
+MODULE_LICENSE("GPL");