Merge tag 'lkdtm-next' of...

Merge tag 'lkdtm-next' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux into char-misc-testing

Kees writes:

refactoring for multiple source files and better layout

drivers/misc/Makefile

@@ -59,7 +59,11 @@ obj-$(CONFIG_CXL_BASE)		+= cxl/
 obj-$(CONFIG_PANEL)             += panel.o
 
 lkdtm-$(CONFIG_LKDTM)		+= lkdtm_core.o
+lkdtm-$(CONFIG_LKDTM)		+= lkdtm_bugs.o
+lkdtm-$(CONFIG_LKDTM)		+= lkdtm_heap.o
+lkdtm-$(CONFIG_LKDTM)		+= lkdtm_perms.o
 lkdtm-$(CONFIG_LKDTM)		+= lkdtm_rodata_objcopy.o
+lkdtm-$(CONFIG_LKDTM)		+= lkdtm_usercopy.o
 
 OBJCOPYFLAGS :=
 OBJCOPYFLAGS_lkdtm_rodata_objcopy.o := \

drivers/misc/lkdtm.h

 #ifndef __LKDTM_H
 #define __LKDTM_H
 
+/* lkdtm_bugs.c */
+void __init lkdtm_bugs_init(int *recur_param);
+void lkdtm_PANIC(void);
+void lkdtm_BUG(void);
+void lkdtm_WARNING(void);
+void lkdtm_EXCEPTION(void);
+void lkdtm_LOOP(void);
+void lkdtm_OVERFLOW(void);
+void lkdtm_CORRUPT_STACK(void);
+void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void);
+void lkdtm_SOFTLOCKUP(void);
+void lkdtm_HARDLOCKUP(void);
+void lkdtm_SPINLOCKUP(void);
+void lkdtm_HUNG_TASK(void);
+void lkdtm_ATOMIC_UNDERFLOW(void);
+void lkdtm_ATOMIC_OVERFLOW(void);
+
+/* lkdtm_heap.c */
+void lkdtm_OVERWRITE_ALLOCATION(void);
+void lkdtm_WRITE_AFTER_FREE(void);
+void lkdtm_READ_AFTER_FREE(void);
+void lkdtm_WRITE_BUDDY_AFTER_FREE(void);
+void lkdtm_READ_BUDDY_AFTER_FREE(void);
+
+/* lkdtm_perms.c */
+void __init lkdtm_perms_init(void);
+void lkdtm_WRITE_RO(void);
+void lkdtm_WRITE_RO_AFTER_INIT(void);
+void lkdtm_WRITE_KERN(void);
+void lkdtm_EXEC_DATA(void);
+void lkdtm_EXEC_STACK(void);
+void lkdtm_EXEC_KMALLOC(void);
+void lkdtm_EXEC_VMALLOC(void);
+void lkdtm_EXEC_RODATA(void);
+void lkdtm_EXEC_USERSPACE(void);
+void lkdtm_ACCESS_USERSPACE(void);
+
+/* lkdtm_rodata.c */
 void lkdtm_rodata_do_nothing(void);
 
+/* lkdtm_usercopy.c */
+void __init lkdtm_usercopy_init(void);
+void __exit lkdtm_usercopy_exit(void);
+void lkdtm_USERCOPY_HEAP_SIZE_TO(void);
+void lkdtm_USERCOPY_HEAP_SIZE_FROM(void);
+void lkdtm_USERCOPY_HEAP_FLAG_TO(void);
+void lkdtm_USERCOPY_HEAP_FLAG_FROM(void);
+void lkdtm_USERCOPY_STACK_FRAME_TO(void);
+void lkdtm_USERCOPY_STACK_FRAME_FROM(void);
+void lkdtm_USERCOPY_STACK_BEYOND(void);
+void lkdtm_USERCOPY_KERNEL(void);
+
+
 #endif

drivers/misc/lkdtm_bugs.c

+/*
+ * This is for all the tests related to logic bugs (e.g. bad dereferences,
+ * bad alignment, bad loops, bad locking, bad scheduling, deep stacks, and
+ * lockups) along with other things that don't fit well into existing LKDTM
+ * test source files.
+ */
+#define pr_fmt(fmt) "lkdtm: " fmt
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+
+#include "lkdtm.h"
+
+/*
+ * Make sure our attempts to over run the kernel stack doesn't trigger
+ * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
+ * recurse past the end of THREAD_SIZE by default.
+ */
+#if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
+#define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2)
+#else
+#define REC_STACK_SIZE (THREAD_SIZE / 8)
+#endif
+#define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
+
+static int recur_count = REC_NUM_DEFAULT;
+
+static DEFINE_SPINLOCK(lock_me_up);
+
+static int recursive_loop(int remaining)
+{
+	char buf[REC_STACK_SIZE];
+
+	/* Make sure compiler does not optimize this away. */
+	memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE);
+	if (!remaining)
+		return 0;
+	else
+		return recursive_loop(remaining - 1);
+}
+
+/* If the depth is negative, use the default, otherwise keep parameter. */
+void __init lkdtm_bugs_init(int *recur_param)
+{
+	if (*recur_param < 0)
+		*recur_param = recur_count;
+	else
+		recur_count = *recur_param;
+}
+
+void lkdtm_PANIC(void)
+{
+	panic("dumptest");
+}
+
+void lkdtm_BUG(void)
+{
+	BUG();
+}
+
+void lkdtm_WARNING(void)
+{
+	WARN_ON(1);
+}
+
+void lkdtm_EXCEPTION(void)
+{
+	*((int *) 0) = 0;
+}
+
+void lkdtm_LOOP(void)
+{
+	for (;;)
+		;
+}
+
+void lkdtm_OVERFLOW(void)
+{
+	(void) recursive_loop(recur_count);
+}
+
+noinline void lkdtm_CORRUPT_STACK(void)
+{
+	/* Use default char array length that triggers stack protection. */
+	char data[8];
+
+	memset((void *)data, 0, 64);
+}
+
+void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void)
+{
+	static u8 data[5] __attribute__((aligned(4))) = {1, 2, 3, 4, 5};
+	u32 *p;
+	u32 val = 0x12345678;
+
+	p = (u32 *)(data + 1);
+	if (*p == 0)
+		val = 0x87654321;
+	*p = val;
+}
+
+void lkdtm_SOFTLOCKUP(void)
+{
+	preempt_disable();
+	for (;;)
+		cpu_relax();
+}
+
+void lkdtm_HARDLOCKUP(void)
+{
+	local_irq_disable();
+	for (;;)
+		cpu_relax();
+}
+
+void lkdtm_SPINLOCKUP(void)
+{
+	/* Must be called twice to trigger. */
+	spin_lock(&lock_me_up);
+	/* Let sparse know we intended to exit holding the lock. */
+	__release(&lock_me_up);
+}
+
+void lkdtm_HUNG_TASK(void)
+{
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	schedule();
+}
+
+void lkdtm_ATOMIC_UNDERFLOW(void)
+{
+	atomic_t under = ATOMIC_INIT(INT_MIN);
+
+	pr_info("attempting good atomic increment\n");
+	atomic_inc(&under);
+	atomic_dec(&under);
+
+	pr_info("attempting bad atomic underflow\n");
+	atomic_dec(&under);
+}
+
+void lkdtm_ATOMIC_OVERFLOW(void)
+{
+	atomic_t over = ATOMIC_INIT(INT_MAX);
+
+	pr_info("attempting good atomic decrement\n");
+	atomic_dec(&over);
+	atomic_inc(&over);
+
+	pr_info("attempting bad atomic overflow\n");
+	atomic_inc(&over);
+}

drivers/misc/lkdtm_heap.c

+/*
+ * This is for all the tests relating directly to heap memory, including
+ * page allocation and slab allocations.
+ */
+#define pr_fmt(fmt) "lkdtm: " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include "lkdtm.h"
+
+/*
+ * This tries to stay within the next largest power-of-2 kmalloc cache
+ * to avoid actually overwriting anything important if it's not detected
+ * correctly.
+ */
+void lkdtm_OVERWRITE_ALLOCATION(void)
+{
+	size_t len = 1020;
+	u32 *data = kmalloc(len, GFP_KERNEL);
+
+	data[1024 / sizeof(u32)] = 0x12345678;
+	kfree(data);
+}
+
+void lkdtm_WRITE_AFTER_FREE(void)
+{
+	int *base, *again;
+	size_t len = 1024;
+	/*
+	 * The slub allocator uses the first word to store the free
+	 * pointer in some configurations. Use the middle of the
+	 * allocation to avoid running into the freelist
+	 */
+	size_t offset = (len / sizeof(*base)) / 2;
+
+	base = kmalloc(len, GFP_KERNEL);
+	pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]);
+	pr_info("Attempting bad write to freed memory at %p\n",
+		&base[offset]);
+	kfree(base);
+	base[offset] = 0x0abcdef0;
+	/* Attempt to notice the overwrite. */
+	again = kmalloc(len, GFP_KERNEL);
+	kfree(again);
+	if (again != base)
+		pr_info("Hmm, didn't get the same memory range.\n");
+}
+
+void lkdtm_READ_AFTER_FREE(void)
+{
+	int *base, *val, saw;
+	size_t len = 1024;
+	/*
+	 * The slub allocator uses the first word to store the free
+	 * pointer in some configurations. Use the middle of the
+	 * allocation to avoid running into the freelist
+	 */
+	size_t offset = (len / sizeof(*base)) / 2;
+
+	base = kmalloc(len, GFP_KERNEL);
+	if (!base) {
+		pr_info("Unable to allocate base memory.\n");
+		return;
+	}
+
+	val = kmalloc(len, GFP_KERNEL);
+	if (!val) {
+		pr_info("Unable to allocate val memory.\n");
+		kfree(base);
+		return;
+	}
+
+	*val = 0x12345678;
+	base[offset] = *val;
+	pr_info("Value in memory before free: %x\n", base[offset]);
+
+	kfree(base);
+
+	pr_info("Attempting bad read from freed memory\n");
+	saw = base[offset];
+	if (saw != *val) {
+		/* Good! Poisoning happened, so declare a win. */
+		pr_info("Memory correctly poisoned (%x)\n", saw);
+		BUG();
+	}
+	pr_info("Memory was not poisoned\n");
+
+	kfree(val);
+}
+
+void lkdtm_WRITE_BUDDY_AFTER_FREE(void)
+{
+	unsigned long p = __get_free_page(GFP_KERNEL);
+	if (!p) {
+		pr_info("Unable to allocate free page\n");
+		return;
+	}
+
+	pr_info("Writing to the buddy page before free\n");
+	memset((void *)p, 0x3, PAGE_SIZE);
+	free_page(p);
+	schedule();
+	pr_info("Attempting bad write to the buddy page after free\n");
+	memset((void *)p, 0x78, PAGE_SIZE);
+	/* Attempt to notice the overwrite. */
+	p = __get_free_page(GFP_KERNEL);
+	free_page(p);
+	schedule();
+}
+
+void lkdtm_READ_BUDDY_AFTER_FREE(void)
+{
+	unsigned long p = __get_free_page(GFP_KERNEL);
+	int saw, *val;
+	int *base;
+
+	if (!p) {
+		pr_info("Unable to allocate free page\n");
+		return;
+	}
+
+	val = kmalloc(1024, GFP_KERNEL);
+	if (!val) {
+		pr_info("Unable to allocate val memory.\n");
+		free_page(p);
+		return;
+	}
+
+	base = (int *)p;
+
+	*val = 0x12345678;
+	base[0] = *val;
+	pr_info("Value in memory before free: %x\n", base[0]);
+	free_page(p);
+	pr_info("Attempting to read from freed memory\n");
+	saw = base[0];
+	if (saw != *val) {
+		/* Good! Poisoning happened, so declare a win. */
+		pr_info("Memory correctly poisoned (%x)\n", saw);
+		BUG();
+	}
+	pr_info("Buddy page was not poisoned\n");
+
+	kfree(val);
+}

drivers/misc/lkdtm_perms.c

+/*
+ * This is for all the tests related to validating kernel memory
+ * permissions: non-executable regions, non-writable regions, and
+ * even non-readable regions.
+ */
+#define pr_fmt(fmt) "lkdtm: " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/mman.h>
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+
+#include "lkdtm.h"
+
+/* Whether or not to fill the target memory area with do_nothing(). */
+#define CODE_WRITE	true
+#define CODE_AS_IS	false
+
+/* How many bytes to copy to be sure we've copied enough of do_nothing(). */
+#define EXEC_SIZE 64
+
+/* This is non-const, so it will end up in the .data section. */
+static u8 data_area[EXEC_SIZE];
+
+/* This is cost, so it will end up in the .rodata section. */
+static const unsigned long rodata = 0xAA55AA55;
+
+/* This is marked __ro_after_init, so it should ultimately be .rodata. */
+static unsigned long ro_after_init __ro_after_init = 0x55AA5500;
+
+/*
+ * This just returns to the caller. It is designed to be copied into
+ * non-executable memory regions.
+ */
+static void do_nothing(void)
+{
+	return;
+}
+
+/* Must immediately follow do_nothing for size calculuations to work out. */
+static void do_overwritten(void)
+{
+	pr_info("do_overwritten wasn't overwritten!\n");
+	return;
+}
+
+static noinline void execute_location(void *dst, bool write)
+{
+	void (*func)(void) = dst;
+
+	pr_info("attempting ok execution at %p\n", do_nothing);
+	do_nothing();
+
+	if (write == CODE_WRITE) {
+		memcpy(dst, do_nothing, EXEC_SIZE);
+		flush_icache_range((unsigned long)dst,
+				   (unsigned long)dst + EXEC_SIZE);
+	}
+	pr_info("attempting bad execution at %p\n", func);
+	func();
+}
+
+static void execute_user_location(void *dst)
+{
+	/* Intentionally crossing kernel/user memory boundary. */
+	void (*func)(void) = dst;
+
+	pr_info("attempting ok execution at %p\n", do_nothing);
+	do_nothing();
+
+	if (copy_to_user((void __user *)dst, do_nothing, EXEC_SIZE))
+		return;
+	flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
+	pr_info("attempting bad execution at %p\n", func);
+	func();
+}
+
+void lkdtm_WRITE_RO(void)
+{
+	/* Explicitly cast away "const" for the test. */
+	unsigned long *ptr = (unsigned long *)&rodata;
+
+	pr_info("attempting bad rodata write at %p\n", ptr);
+	*ptr ^= 0xabcd1234;
+}
+
+void lkdtm_WRITE_RO_AFTER_INIT(void)
+{
+	unsigned long *ptr = &ro_after_init;
+
+	/*
+	 * Verify we were written to during init. Since an Oops
+	 * is considered a "success", a failure is to just skip the
+	 * real test.
+	 */
+	if ((*ptr & 0xAA) != 0xAA) {
+		pr_info("%p was NOT written during init!?\n", ptr);
+		return;
+	}
+
+	pr_info("attempting bad ro_after_init write at %p\n", ptr);
+	*ptr ^= 0xabcd1234;
+}
+
+void lkdtm_WRITE_KERN(void)
+{
+	size_t size;
+	unsigned char *ptr;
+
+	size = (unsigned long)do_overwritten - (unsigned long)do_nothing;
+	ptr = (unsigned char *)do_overwritten;
+
+	pr_info("attempting bad %zu byte write at %p\n", size, ptr);
+	memcpy(ptr, (unsigned char *)do_nothing, size);
+	flush_icache_range((unsigned long)ptr, (unsigned long)(ptr + size));
+
+	do_overwritten();
+}
+
+void lkdtm_EXEC_DATA(void)
+{
+	execute_location(data_area, CODE_WRITE);
+}
+
+void lkdtm_EXEC_STACK(void)
+{
+	u8 stack_area[EXEC_SIZE];
+	execute_location(stack_area, CODE_WRITE);
+}
+
+void lkdtm_EXEC_KMALLOC(void)
+{
+	u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL);
+	execute_location(kmalloc_area, CODE_WRITE);
+	kfree(kmalloc_area);
+}
+
+void lkdtm_EXEC_VMALLOC(void)
+{
+	u32 *vmalloc_area = vmalloc(EXEC_SIZE);
+	execute_location(vmalloc_area, CODE_WRITE);
+	vfree(vmalloc_area);
+}
+
+void lkdtm_EXEC_RODATA(void)
+{
+	execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS);
+}
+
+void lkdtm_EXEC_USERSPACE(void)
+{
+	unsigned long user_addr;
+
+	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+			    PROT_READ | PROT_WRITE | PROT_EXEC,
+			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+	if (user_addr >= TASK_SIZE) {
+		pr_warn("Failed to allocate user memory\n");
+		return;
+	}
+	execute_user_location((void *)user_addr);
+	vm_munmap(user_addr, PAGE_SIZE);
+}
+
+void lkdtm_ACCESS_USERSPACE(void)
+{
+	unsigned long user_addr, tmp = 0;
+	unsigned long *ptr;
+
+	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+			    PROT_READ | PROT_WRITE | PROT_EXEC,
+			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+	if (user_addr >= TASK_SIZE) {
+		pr_warn("Failed to allocate user memory\n");
+		return;
+	}
+
+	if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) {
+		pr_warn("copy_to_user failed\n");
+		vm_munmap(user_addr, PAGE_SIZE);
+		return;
+	}
+
+	ptr = (unsigned long *)user_addr;
+
+	pr_info("attempting bad read at %p\n", ptr);
+	tmp = *ptr;
+	tmp += 0xc0dec0de;
+
+	pr_info("attempting bad write at %p\n", ptr);
+	*ptr = tmp;
+
+	vm_munmap(user_addr, PAGE_SIZE);
+}
+
+void __init lkdtm_perms_init(void)
+{
+	/* Make sure we can write to __ro_after_init values during __init */
+	ro_after_init |= 0xAA;
+
+}

drivers/misc/lkdtm_usercopy.c

+/*
+ * This is for all the tests related to copy_to_user() and copy_from_user()
+ * hardening.
+ */
+#define pr_fmt(fmt) "lkdtm: " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/mman.h>
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+
+static size_t cache_size = 1024;
+static struct kmem_cache *bad_cache;
+
+static const unsigned char test_text[] = "This is a test.\n";
+
+/*
+ * Instead of adding -Wno-return-local-addr, just pass the stack address
+ * through a function to obfuscate it from the compiler.
+ */
+static noinline unsigned char *trick_compiler(unsigned char *stack)
+{
+	return stack + 0;
+}
+
+static noinline unsigned char *do_usercopy_stack_callee(int value)
+{
+	unsigned char buf[32];
+	int i;
+
+	/* Exercise stack to avoid everything living in registers. */
+	for (i = 0; i < sizeof(buf); i++) {
+		buf[i] = value & 0xff;
+	}
+
+	return trick_compiler(buf);
+}
+
+static noinline void do_usercopy_stack(bool to_user, bool bad_frame)
+{
+	unsigned long user_addr;
+	unsigned char good_stack[32];
+	unsigned char *bad_stack;
+	int i;
+
+	/* Exercise stack to avoid everything living in registers. */
+	for (i = 0; i < sizeof(good_stack); i++)
+		good_stack[i] = test_text[i % sizeof(test_text)];
+
+	/* This is a pointer to outside our current stack frame. */
+	if (bad_frame) {
+		bad_stack = do_usercopy_stack_callee((uintptr_t)bad_stack);
+	} else {
+		/* Put start address just inside stack. */
+		bad_stack = task_stack_page(current) + THREAD_SIZE;
+		bad_stack -= sizeof(unsigned long);
+	}
+
+	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+			    PROT_READ | PROT_WRITE | PROT_EXEC,
+			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+	if (user_addr >= TASK_SIZE) {
+		pr_warn("Failed to allocate user memory\n");
+		return;
+	}
+
+	if (to_user) {
+		pr_info("attempting good copy_to_user of local stack\n");
+		if (copy_to_user((void __user *)user_addr, good_stack,
+				 sizeof(good_stack))) {
+			pr_warn("copy_to_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_to_user of distant stack\n");
+		if (copy_to_user((void __user *)user_addr, bad_stack,
+				 sizeof(good_stack))) {
+			pr_warn("copy_to_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	} else {
+		/*
+		 * There isn't a safe way to not be protected by usercopy
+		 * if we're going to write to another thread's stack.
+		 */
+		if (!bad_frame)
+			goto free_user;
+
+		pr_info("attempting good copy_from_user of local stack\n");
+		if (copy_from_user(good_stack, (void __user *)user_addr,
+				   sizeof(good_stack))) {
+			pr_warn("copy_from_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_from_user of distant stack\n");
+		if (copy_from_user(bad_stack, (void __user *)user_addr,
+				   sizeof(good_stack))) {
+			pr_warn("copy_from_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	}
+
+free_user:
+	vm_munmap(user_addr, PAGE_SIZE);
+}
+
+static void do_usercopy_heap_size(bool to_user)
+{
+	unsigned long user_addr;
+	unsigned char *one, *two;
+	const size_t size = 1024;
+
+	one = kmalloc(size, GFP_KERNEL);
+	two = kmalloc(size, GFP_KERNEL);
+	if (!one || !two) {
+		pr_warn("Failed to allocate kernel memory\n");
+		goto free_kernel;
+	}
+
+	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+			    PROT_READ | PROT_WRITE | PROT_EXEC,
+			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+	if (user_addr >= TASK_SIZE) {
+		pr_warn("Failed to allocate user memory\n");
+		goto free_kernel;
+	}
+
+	memset(one, 'A', size);
+	memset(two, 'B', size);
+
+	if (to_user) {
+		pr_info("attempting good copy_to_user of correct size\n");
+		if (copy_to_user((void __user *)user_addr, one, size)) {
+			pr_warn("copy_to_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_to_user of too large size\n");
+		if (copy_to_user((void __user *)user_addr, one, 2 * size)) {
+			pr_warn("copy_to_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	} else {
+		pr_info("attempting good copy_from_user of correct size\n");
+		if (copy_from_user(one, (void __user *)user_addr, size)) {
+			pr_warn("copy_from_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_from_user of too large size\n");
+		if (copy_from_user(one, (void __user *)user_addr, 2 * size)) {
+			pr_warn("copy_from_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	}
+
+free_user:
+	vm_munmap(user_addr, PAGE_SIZE);
+free_kernel:
+	kfree(one);
+	kfree(two);
+}
+
+static void do_usercopy_heap_flag(bool to_user)
+{
+	unsigned long user_addr;
+	unsigned char *good_buf = NULL;
+	unsigned char *bad_buf = NULL;
+
+	/* Make sure cache was prepared. */
+	if (!bad_cache) {
+		pr_warn("Failed to allocate kernel cache\n");
+		return;
+	}
+
+	/*
+	 * Allocate one buffer from each cache (kmalloc will have the
+	 * SLAB_USERCOPY flag already, but "bad_cache" won't).
+	 */
+	good_buf = kmalloc(cache_size, GFP_KERNEL);
+	bad_buf = kmem_cache_alloc(bad_cache, GFP_KERNEL);
+	if (!good_buf || !bad_buf) {
+		pr_warn("Failed to allocate buffers from caches\n");
+		goto free_alloc;
+	}
+
+	/* Allocate user memory we'll poke at. */
+	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+			    PROT_READ | PROT_WRITE | PROT_EXEC,
+			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+	if (user_addr >= TASK_SIZE) {
+		pr_warn("Failed to allocate user memory\n");
+		goto free_alloc;
+	}
+
+	memset(good_buf, 'A', cache_size);
+	memset(bad_buf, 'B', cache_size);
+
+	if (to_user) {
+		pr_info("attempting good copy_to_user with SLAB_USERCOPY\n");
+		if (copy_to_user((void __user *)user_addr, good_buf,
+				 cache_size)) {
+			pr_warn("copy_to_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_to_user w/o SLAB_USERCOPY\n");
+		if (copy_to_user((void __user *)user_addr, bad_buf,
+				 cache_size)) {
+			pr_warn("copy_to_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	} else {
+		pr_info("attempting good copy_from_user with SLAB_USERCOPY\n");
+		if (copy_from_user(good_buf, (void __user *)user_addr,
+				   cache_size)) {
+			pr_warn("copy_from_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_from_user w/o SLAB_USERCOPY\n");
+		if (copy_from_user(bad_buf, (void __user *)user_addr,
+				   cache_size)) {
+			pr_warn("copy_from_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	}
+
+free_user:
+	vm_munmap(user_addr, PAGE_SIZE);
+free_alloc:
+	if (bad_buf)
+		kmem_cache_free(bad_cache, bad_buf);
+	kfree(good_buf);
+}
+
+/* Callable tests. */
+void lkdtm_USERCOPY_HEAP_SIZE_TO(void)
+{
+	do_usercopy_heap_size(true);
+}
+
+void lkdtm_USERCOPY_HEAP_SIZE_FROM(void)
+{
+	do_usercopy_heap_size(false);
+}
+
+void lkdtm_USERCOPY_HEAP_FLAG_TO(void)
+{
+	do_usercopy_heap_flag(true);
+}
+
+void lkdtm_USERCOPY_HEAP_FLAG_FROM(void)
+{
+	do_usercopy_heap_flag(false);
+}
+
+void lkdtm_USERCOPY_STACK_FRAME_TO(void)
+{
+	do_usercopy_stack(true, true);
+}
+
+void lkdtm_USERCOPY_STACK_FRAME_FROM(void)
+{
+	do_usercopy_stack(false, true);
+}
+
+void lkdtm_USERCOPY_STACK_BEYOND(void)
+{
+	do_usercopy_stack(true, false);
+}
+
+void lkdtm_USERCOPY_KERNEL(void)
+{
+	unsigned long user_addr;
+
+	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+			    PROT_READ | PROT_WRITE | PROT_EXEC,
+			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+	if (user_addr >= TASK_SIZE) {
+		pr_warn("Failed to allocate user memory\n");
+		return;
+	}
+
+	pr_info("attempting good copy_to_user from kernel rodata\n");
+	if (copy_to_user((void __user *)user_addr, test_text,
+			 sizeof(test_text))) {
+		pr_warn("copy_to_user failed unexpectedly?!\n");
+		goto free_user;
+	}
+
+	pr_info("attempting bad copy_to_user from kernel text\n");
+	if (copy_to_user((void __user *)user_addr, vm_mmap, PAGE_SIZE)) {
+		pr_warn("copy_to_user failed, but lacked Oops\n");
+		goto free_user;
+	}
+
+free_user:
+	vm_munmap(user_addr, PAGE_SIZE);
+}
+
+void __init lkdtm_usercopy_init(void)
+{
+	/* Prepare cache that lacks SLAB_USERCOPY flag. */
+	bad_cache = kmem_cache_create("lkdtm-no-usercopy", cache_size, 0,
+				      0, NULL);
+}
+
+void __exit lkdtm_usercopy_exit(void)
+{
+	kmem_cache_destroy(bad_cache);
+}