Commit 966fede8 authored by Kees Cook's avatar Kees Cook Committed by Linus Torvalds
Browse files

lkdtm/heap: add tests for freelist hardening 

This adds tests for double free and cross-cache freeing, which should both
be caught by CONFIG_SLAB_FREELIST_HARDENED.

Link: http://lkml.kernel.org/r/20190530045017.15252-4-keescook@chromium.org


Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Cc: Alexander Popov <alex.popov@linux.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a64b5378

drivers/misc/lkdtm/core.c

+5 −0
Original line number Diff line number Diff line
@@ -120,6 +120,9 @@ static const struct crashtype crashtypes[] = { 
	CRASHTYPE(READ_AFTER_FREE),

	CRASHTYPE(WRITE_BUDDY_AFTER_FREE),

	CRASHTYPE(READ_BUDDY_AFTER_FREE),

	CRASHTYPE(SLAB_FREE_DOUBLE),

	CRASHTYPE(SLAB_FREE_CROSS),

	CRASHTYPE(SLAB_FREE_PAGE),

	CRASHTYPE(SOFTLOCKUP),

	CRASHTYPE(HARDLOCKUP),

	CRASHTYPE(SPINLOCKUP),
@@ -426,6 +429,7 @@ static int __init lkdtm_module_init(void) 
	lkdtm_bugs_init(&recur_count);

	lkdtm_perms_init();

	lkdtm_usercopy_init();

	lkdtm_heap_init();



	/* Register debugfs interface */

	lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
@@ -472,6 +476,7 @@ static void __exit lkdtm_module_exit(void) 
	debugfs_remove_recursive(lkdtm_debugfs_root);



	/* Handle test-specific clean-up. */

	lkdtm_heap_exit();

	lkdtm_usercopy_exit();



	if (lkdtm_kprobe != NULL)

drivers/misc/lkdtm/heap.c

+72 −0
Original line number Diff line number Diff line
@@ -7,6 +7,10 @@ 
#include <linux/slab.h>

#include <linux/sched.h>



static struct kmem_cache *double_free_cache;

static struct kmem_cache *a_cache;

static struct kmem_cache *b_cache;



/*

 * This tries to stay within the next largest power-of-2 kmalloc cache

 * to avoid actually overwriting anything important if it's not detected
@@ -146,3 +150,71 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void) 


	kfree(val);

}



void lkdtm_SLAB_FREE_DOUBLE(void)

{

	int *val;



	val = kmem_cache_alloc(double_free_cache, GFP_KERNEL);

	if (!val) {

		pr_info("Unable to allocate double_free_cache memory.\n");

		return;

	}



	/* Just make sure we got real memory. */

	*val = 0x12345678;

	pr_info("Attempting double slab free ...\n");

	kmem_cache_free(double_free_cache, val);

	kmem_cache_free(double_free_cache, val);

}



void lkdtm_SLAB_FREE_CROSS(void)

{

	int *val;



	val = kmem_cache_alloc(a_cache, GFP_KERNEL);

	if (!val) {

		pr_info("Unable to allocate a_cache memory.\n");

		return;

	}



	/* Just make sure we got real memory. */

	*val = 0x12345679;

	pr_info("Attempting cross-cache slab free ...\n");

	kmem_cache_free(b_cache, val);

}



void lkdtm_SLAB_FREE_PAGE(void)

{

	unsigned long p = __get_free_page(GFP_KERNEL);



	pr_info("Attempting non-Slab slab free ...\n");

	kmem_cache_free(NULL, (void *)p);

	free_page(p);

}



/*

 * We have constructors to keep the caches distinctly separated without

 * needing to boot with "slab_nomerge".

 */

static void ctor_double_free(void *region)

{ }

static void ctor_a(void *region)

{ }

static void ctor_b(void *region)

{ }



void __init lkdtm_heap_init(void)

{

	double_free_cache = kmem_cache_create("lkdtm-heap-double_free",

					      64, 0, 0, ctor_double_free);

	a_cache = kmem_cache_create("lkdtm-heap-a", 64, 0, 0, ctor_a);

	b_cache = kmem_cache_create("lkdtm-heap-b", 64, 0, 0, ctor_b);

}



void __exit lkdtm_heap_exit(void)

{

	kmem_cache_destroy(double_free_cache);

	kmem_cache_destroy(a_cache);

	kmem_cache_destroy(b_cache);

}

drivers/misc/lkdtm/lkdtm.h

+5 −0
Original line number Diff line number Diff line
@@ -28,11 +28,16 @@ void lkdtm_STACK_GUARD_PAGE_LEADING(void); 
void lkdtm_STACK_GUARD_PAGE_TRAILING(void);



/* lkdtm_heap.c */

void __init lkdtm_heap_init(void);

void __exit lkdtm_heap_exit(void);

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);

void lkdtm_SLAB_FREE_DOUBLE(void);

void lkdtm_SLAB_FREE_CROSS(void);

void lkdtm_SLAB_FREE_PAGE(void);



/* lkdtm_perms.c */

void __init lkdtm_perms_init(void);

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