Merge tag 'hardening-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull kernel hardening updates from Kees Cook:

 - Add arm64 Shadow Call Stack support for GCC 12 (Dan Li)

 - Avoid memset with stack offset randomization under Clang (Marco
   Elver)

 - Clean up stackleak plugin to play nice with .noinstr (Kees Cook)

 - Check stack depth for greater usercopy hardening coverage (Kees Cook)

* tag 'hardening-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  arm64: Add gcc Shadow Call Stack support
  m68k: Implement "current_stack_pointer"
  xtensa: Implement "current_stack_pointer"
  usercopy: Check valid lifetime via stack depth
  stack: Constrain and fix stack offset randomization with Clang builds
  stack: Introduce CONFIG_RANDOMIZE_KSTACK_OFFSET
  gcc-plugins/stackleak: Ignore .noinstr.text and .entry.text
  gcc-plugins/stackleak: Exactly match strings instead of prefixes
  gcc-plugins/stackleak: Provide verbose mode

1 files changed, 25 insertions, 4 deletions

diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c
index e9db7dcb3e5f..42f0252ee2a4 100644
--- a/scripts/gcc-plugins/stackleak_plugin.c
+++ b/scripts/gcc-plugins/stackleak_plugin.c
@@ -429,6 +429,23 @@ static unsigned int stackleak_cleanup_execute(void)
 	return 0;
 }
 
+/*
+ * STRING_CST may or may not be NUL terminated:
+ * https://gcc.gnu.org/onlinedocs/gccint/Constant-expressions.html
+ */
+static inline bool string_equal(tree node, const char *string, int length)
+{
+	if (TREE_STRING_LENGTH(node) < length)
+		return false;
+	if (TREE_STRING_LENGTH(node) > length + 1)
+		return false;
+	if (TREE_STRING_LENGTH(node) == length + 1 &&
+	    TREE_STRING_POINTER(node)[length] != '\0')
+		return false;
+	return !memcmp(TREE_STRING_POINTER(node), string, length);
+}
+#define STRING_EQUAL(node, str)	string_equal(node, str, strlen(str))
+
 static bool stackleak_gate(void)
 {
 	tree section;
@@ -438,13 +455,17 @@ static bool stackleak_gate(void)
 	if (section && TREE_VALUE(section)) {
 		section = TREE_VALUE(TREE_VALUE(section));
 
-		if (!strncmp(TREE_STRING_POINTER(section), ".init.text", 10))
+		if (STRING_EQUAL(section, ".init.text"))
+			return false;
+		if (STRING_EQUAL(section, ".devinit.text"))
+			return false;
+		if (STRING_EQUAL(section, ".cpuinit.text"))
 			return false;
-		if (!strncmp(TREE_STRING_POINTER(section), ".devinit.text", 13))
+		if (STRING_EQUAL(section, ".meminit.text"))
 			return false;
-		if (!strncmp(TREE_STRING_POINTER(section), ".cpuinit.text", 13))
+		if (STRING_EQUAL(section, ".noinstr.text"))
 			return false;
-		if (!strncmp(TREE_STRING_POINTER(section), ".meminit.text", 13))
+		if (STRING_EQUAL(section, ".entry.text"))
 			return false;
 	}