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Code Issues Releases Wiki Activity

lkdtm: drop "alloc_size" parameter

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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: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2016-06-26 08:51:14 -07:00
parent 6c3521400c
commit 0edca7b5af
1 changed files with 5 additions and 10 deletions
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15
drivers/misc/lkdtm_core.c
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@ -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);