lkml.org 
[lkml]   [2016]   [Jul]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 02/12] lkdtm: drop "alloc_size" parameter
Date
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>
---
drivers/misc/lkdtm_core.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index 23d222a6c77d..80e7a46db178 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -185,8 +185,6 @@ 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;
@@ -195,6 +193,8 @@ 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";
@@ -211,9 +211,6 @@ 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)
{
@@ -442,7 +439,7 @@ 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;
@@ -531,7 +528,7 @@ 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);
@@ -565,8 +562,7 @@ 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;
}
@@ -1285,7 +1281,6 @@ 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);

--
2.7.4
\
 
 \ /
  Last update: 2016-07-07 01:21    [W:0.065 / U:23.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site