test_overflow: Add memory allocation overflow tests

Make sure that the memory allocators are behaving as expected in the face
of overflows of multiplied arguments or when using the array_size()-family
helpers.

Example output of new tests (with the expected __alloc_pages_slowpath
and vmalloc warnings about refusing giant allocations removed):

[   93.062076] test_overflow: kmalloc detected saturation
[   93.062988] test_overflow: kmalloc_node detected saturation
[   93.063818] test_overflow: kzalloc detected saturation
[   93.064539] test_overflow: kzalloc_node detected saturation
[   93.120386] test_overflow: kvmalloc detected saturation
[   93.143458] test_overflow: kvmalloc_node detected saturation
[   93.166861] test_overflow: kvzalloc detected saturation
[   93.189924] test_overflow: kvzalloc_node detected saturation
[   93.221671] test_overflow: vmalloc detected saturation
[   93.246326] test_overflow: vmalloc_node detected saturation
[   93.270260] test_overflow: vzalloc detected saturation
[   93.293824] test_overflow: vzalloc_node detected saturation
[   93.294597] test_overflow: devm_kmalloc detected saturation
[   93.295383] test_overflow: devm_kzalloc detected saturation
[   93.296217] test_overflow: all tests passed
Signed-off-by: NKees Cook <keescook@chromium.org>

lib/test_overflow.c

@@ -4,11 +4,15 @@
  */
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/device.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/overflow.h>
+#include <linux/slab.h>
 #include <linux/types.h>
+#include <linux/vmalloc.h>
 
 #define DEFINE_TEST_ARRAY(t)			\
 	static const struct test_ ## t {	\
@@ -283,11 +287,117 @@ static int __init test_overflow_calculation(void)
 	return err;
 }
 
+/*
+ * Deal with the various forms of allocator arguments. See comments above
+ * the DEFINE_TEST_ALLOC() instances for mapping of the "bits".
+ */
+#define alloc010(alloc, arg, sz) alloc(sz, GFP_KERNEL)
+#define alloc011(alloc, arg, sz) alloc(sz, GFP_KERNEL, NUMA_NO_NODE)
+#define alloc000(alloc, arg, sz) alloc(sz)
+#define alloc001(alloc, arg, sz) alloc(sz, NUMA_NO_NODE)
+#define alloc110(alloc, arg, sz) alloc(arg, sz, GFP_KERNEL)
+#define free0(free, arg, ptr)	 free(ptr)
+#define free1(free, arg, ptr)	 free(arg, ptr)
+
+/* Wrap around to 8K */
+#define TEST_SIZE		(9 << PAGE_SHIFT)
+
+#define DEFINE_TEST_ALLOC(func, free_func, want_arg, want_gfp, want_node)\
+static int __init test_ ## func (void *arg)				\
+{									\
+	volatile size_t a = TEST_SIZE;					\
+	volatile size_t b = (SIZE_MAX / TEST_SIZE) + 1;			\
+	void *ptr;							\
+									\
+	/* Tiny allocation test. */					\
+	ptr = alloc ## want_arg ## want_gfp ## want_node (func, arg, 1);\
+	if (!ptr) {							\
+		pr_warn(#func " failed regular allocation?!\n");	\
+		return 1;						\
+	}								\
+	free ## want_arg (free_func, arg, ptr);				\
+									\
+	/* Wrapped allocation test. */					\
+	ptr = alloc ## want_arg ## want_gfp ## want_node (func, arg,	\
+							  a * b);	\
+	if (!ptr) {							\
+		pr_warn(#func " unexpectedly failed bad wrapping?!\n");	\
+		return 1;						\
+	}								\
+	free ## want_arg (free_func, arg, ptr);				\
+									\
+	/* Saturated allocation test. */				\
+	ptr = alloc ## want_arg ## want_gfp ## want_node (func, arg,	\
+						   array_size(a, b));	\
+	if (ptr) {							\
+		pr_warn(#func " missed saturation!\n");			\
+		free ## want_arg (free_func, arg, ptr);			\
+		return 1;						\
+	}								\
+	pr_info(#func " detected saturation\n");			\
+	return 0;							\
+}
+
+/*
+ * Allocator uses a trailing node argument --------+  (e.g. kmalloc_node())
+ * Allocator uses the gfp_t argument -----------+  |  (e.g. kmalloc())
+ * Allocator uses a special leading argument +  |  |  (e.g. devm_kmalloc())
+ *                                           |  |  |
+ */
+DEFINE_TEST_ALLOC(kmalloc,	 kfree,	     0, 1, 0);
+DEFINE_TEST_ALLOC(kmalloc_node,	 kfree,	     0, 1, 1);
+DEFINE_TEST_ALLOC(kzalloc,	 kfree,	     0, 1, 0);
+DEFINE_TEST_ALLOC(kzalloc_node,  kfree,	     0, 1, 1);
+DEFINE_TEST_ALLOC(vmalloc,	 vfree,	     0, 0, 0);
+DEFINE_TEST_ALLOC(vmalloc_node,  vfree,	     0, 0, 1);
+DEFINE_TEST_ALLOC(vzalloc,	 vfree,	     0, 0, 0);
+DEFINE_TEST_ALLOC(vzalloc_node,  vfree,	     0, 0, 1);
+DEFINE_TEST_ALLOC(kvmalloc,	 kvfree,     0, 1, 0);
+DEFINE_TEST_ALLOC(kvmalloc_node, kvfree,     0, 1, 1);
+DEFINE_TEST_ALLOC(kvzalloc,	 kvfree,     0, 1, 0);
+DEFINE_TEST_ALLOC(kvzalloc_node, kvfree,     0, 1, 1);
+DEFINE_TEST_ALLOC(devm_kmalloc,  devm_kfree, 1, 1, 0);
+DEFINE_TEST_ALLOC(devm_kzalloc,  devm_kfree, 1, 1, 0);
+
+static int __init test_overflow_allocation(void)
+{
+	const char device_name[] = "overflow-test";
+	struct device *dev;
+	int err = 0;
+
+	/* Create dummy device for devm_kmalloc()-family tests. */
+	dev = root_device_register(device_name);
+	if (!dev) {
+		pr_warn("Cannot register test device\n");
+		return 1;
+	}
+
+	err |= test_kmalloc(NULL);
+	err |= test_kmalloc_node(NULL);
+	err |= test_kzalloc(NULL);
+	err |= test_kzalloc_node(NULL);
+	err |= test_kvmalloc(NULL);
+	err |= test_kvmalloc_node(NULL);
+	err |= test_kvzalloc(NULL);
+	err |= test_kvzalloc_node(NULL);
+	err |= test_vmalloc(NULL);
+	err |= test_vmalloc_node(NULL);
+	err |= test_vzalloc(NULL);
+	err |= test_vzalloc_node(NULL);
+	err |= test_devm_kmalloc(dev);
+	err |= test_devm_kzalloc(dev);
+
+	device_unregister(dev);
+
+	return err;
+}
+
 static int __init test_module_init(void)
 {
 	int err = 0;
 
 	err |= test_overflow_calculation();
+	err |= test_overflow_allocation();
 
 	if (err) {
 		pr_warn("FAIL!\n");