strlen_overflow and CONFIG_FORTIFY_SOURCE

kernel_module/README.adoc

@@ -45,6 +45,8 @@
 .. link:netlink.c[]
 . Utilities
 .. link:kstrto.c[]
+. Hardening
+.. link:strlen_overflow.c[]
 . Arch
 .. x86
 ... link:ring0.c[]

kernel_module/strlen_overflow.c

@@ -0,0 +1,24 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+
+static int myinit(void)
+{
+	enum { size = 256 };
+	int i = 1;
+	char buf[size];
+	char buf2[size];
+	for (i = 0; i < size; i++) {
+		buf[i] = 'a';
+		buf2[i] = 'b';
+	}
+	/*char buf[] = {'p', 'w', 'n'};*/
+	pr_info("%llu\n", (long long unsigned)strlen(buf));
+	return 0;
+}
+
+static void myexit(void) {}
+
+module_init(myinit)
+module_exit(myexit)
+MODULE_LICENSE("GPL");