Commit ca90800a authored by Kees Cook's avatar Kees Cook
Browse files

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: default avatarKees Cook <keescook@chromium.org>
parent 610b15c5

lib/test_overflow.c

+110 −0
Original line number Diff line number Diff line
@@ -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");

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