Commit 9c4f6ebc authored by Kees Cook's avatar Kees Cook Committed by Greg Kroah-Hartman
Browse files

lkdtm/heap: Add vmalloc linear overflow test 



Similar to the existing slab overflow and stack exhaustion tests, add
VMALLOC_LINEAR_OVERFLOW (and rename the slab test SLAB_LINEAR_OVERFLOW).
Additionally unmarks the test as destructive. (It should be safe in the
face of misbehavior.)

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210623203936.3151093-6-keescook@chromium.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a15676ac

drivers/misc/lkdtm/core.c

+2 −1
Original line number Diff line number Diff line
@@ -120,7 +120,8 @@ static const struct crashtype crashtypes[] = { 
	CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),

	CRASHTYPE(FORTIFY_OBJECT),

	CRASHTYPE(FORTIFY_SUBOBJECT),

	CRASHTYPE(OVERWRITE_ALLOCATION),

	CRASHTYPE(SLAB_LINEAR_OVERFLOW),

	CRASHTYPE(VMALLOC_LINEAR_OVERFLOW),

	CRASHTYPE(WRITE_AFTER_FREE),

	CRASHTYPE(READ_AFTER_FREE),

	CRASHTYPE(WRITE_BUDDY_AFTER_FREE),

drivers/misc/lkdtm/heap.c

+21 −1
Original line number Diff line number Diff line
@@ -5,24 +5,44 @@ 
 */

#include "lkdtm.h"

#include <linux/slab.h>

#include <linux/vmalloc.h>

#include <linux/sched.h>



static struct kmem_cache *double_free_cache;

static struct kmem_cache *a_cache;

static struct kmem_cache *b_cache;



/*

 * If there aren't guard pages, it's likely that a consecutive allocation will

 * let us overflow into the second allocation without overwriting something real.

 */

void lkdtm_VMALLOC_LINEAR_OVERFLOW(void)

{

	char *one, *two;



	one = vzalloc(PAGE_SIZE);

	two = vzalloc(PAGE_SIZE);



	pr_info("Attempting vmalloc linear overflow ...\n");

	memset(one, 0xAA, PAGE_SIZE + 1);



	vfree(two);

	vfree(one);

}



/*

 * 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)

void lkdtm_SLAB_LINEAR_OVERFLOW(void)

{

	size_t len = 1020;

	u32 *data = kmalloc(len, GFP_KERNEL);

	if (!data)

		return;



	pr_info("Attempting slab linear overflow ...\n");

	data[1024 / sizeof(u32)] = 0x12345678;

	kfree(data);

}

drivers/misc/lkdtm/lkdtm.h

+2 −1
Original line number Diff line number Diff line
@@ -39,7 +39,8 @@ void lkdtm_FORTIFY_SUBOBJECT(void); 
/* heap.c */

void __init lkdtm_heap_init(void);

void __exit lkdtm_heap_exit(void);

void lkdtm_OVERWRITE_ALLOCATION(void);

void lkdtm_VMALLOC_LINEAR_OVERFLOW(void);

void lkdtm_SLAB_LINEAR_OVERFLOW(void);

void lkdtm_WRITE_AFTER_FREE(void);

void lkdtm_READ_AFTER_FREE(void);

void lkdtm_WRITE_BUDDY_AFTER_FREE(void);

tools/testing/selftests/lkdtm/tests.txt

+2 −1
Original line number Diff line number Diff line
@@ -15,7 +15,8 @@ UNSET_SMEP pinned CR4 bits changed: 
DOUBLE_FAULT

CORRUPT_PAC

UNALIGNED_LOAD_STORE_WRITE

#OVERWRITE_ALLOCATION Corrupts memory on failure

SLAB_LINEAR_OVERFLOW

VMALLOC_LINEAR_OVERFLOW

#WRITE_AFTER_FREE Corrupts memory on failure

READ_AFTER_FREE call trace:|Memory correctly poisoned

#WRITE_BUDDY_AFTER_FREE Corrupts memory on failure