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Commit 0edca7b5 authored by Kees Cook's avatar Kees Cook
Browse files

lkdtm: drop "alloc_size" parameter 



There is no good reason to have the alloc_size parameter currently. The
compiler-tricking value used to exercise the stack can just use a stack
address instead. Similarly hard-code cache_size.

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent 6c352140

drivers/misc/lkdtm_core.c

+5 −10
Original line number Diff line number Diff line
@@ -184,8 +184,6 @@ static char* cpoint_name; 
static char* cpoint_type;

static int cpoint_count = DEFAULT_COUNT;

static int recur_count = REC_NUM_DEFAULT;

static int alloc_size = 1024;

static size_t cache_size;



static enum cname cpoint = CN_INVALID;

static enum ctype cptype = CT_NONE;
@@ -194,6 +192,8 @@ static DEFINE_SPINLOCK(count_lock); 
static DEFINE_SPINLOCK(lock_me_up);



static u8 data_area[EXEC_SIZE];



static size_t cache_size = 1024;

static struct kmem_cache *bad_cache;



static const unsigned char test_text[] = "This is a test.\n";
@@ -210,9 +210,6 @@ MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\ 
module_param(cpoint_count, int, 0644);

MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\

				"crash point is to be hit to trigger action");

module_param(alloc_size, int, 0644);

MODULE_PARM_DESC(alloc_size, " Size of allocation for user copy tests "\

			     "(from 1 to PAGE_SIZE)");



static unsigned int jp_do_irq(unsigned int irq)

{
@@ -441,7 +438,7 @@ static noinline void do_usercopy_stack(bool to_user, bool bad_frame) 


	/* This is a pointer to outside our current stack frame. */

	if (bad_frame) {

		bad_stack = do_usercopy_stack_callee(alloc_size);

		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;
@@ -530,7 +527,7 @@ static void do_usercopy_heap_size(bool to_user) 
{

	unsigned long user_addr;

	unsigned char *one, *two;

	size_t size = clamp_t(int, alloc_size, 1, PAGE_SIZE);

	size_t size = 1024;



	one = kmalloc(size, GFP_KERNEL);

	two = kmalloc(size, GFP_KERNEL);
@@ -564,8 +561,7 @@ static void do_usercopy_heap_size(bool to_user) 
		}

	} else {

		pr_info("attempting good copy_from_user of correct size\n");

		if (copy_from_user(one, (void __user *)user_addr,

				   size)) {

		if (copy_from_user(one, (void __user *)user_addr, size)) {

			pr_warn("copy_from_user failed unexpectedly?!\n");

			goto free_user;

		}
@@ -1284,7 +1280,6 @@ static int __init lkdtm_module_init(void) 
	ro_after_init |= 0xAA;



	/* Prepare cache that lacks SLAB_USERCOPY flag. */

	cache_size = clamp_t(int, alloc_size, 1, PAGE_SIZE);

	bad_cache = kmem_cache_create("lkdtm-no-usercopy", cache_size, 0,

				      0, NULL);