diff options
Diffstat (limited to 'drivers/misc/lkdtm_usercopy.c')
| -rw-r--r-- | drivers/misc/lkdtm_usercopy.c | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/drivers/misc/lkdtm_usercopy.c b/drivers/misc/lkdtm_usercopy.c index 5a3fd76eec27..1dd611423d8b 100644 --- a/drivers/misc/lkdtm_usercopy.c +++ b/drivers/misc/lkdtm_usercopy.c @@ -9,7 +9,15 @@ #include <linux/uaccess.h> #include <asm/cacheflush.h> -static size_t cache_size = 1024; +/* + * Many of the tests here end up using const sizes, but those would + * normally be ignored by hardened usercopy, so force the compiler + * into choosing the non-const path to make sure we trigger the + * hardened usercopy checks by added "unconst" to all the const copies, + * and making sure "cache_size" isn't optimized into a const. + */ +static volatile size_t unconst = 0; +static volatile size_t cache_size = 1024; static struct kmem_cache *bad_cache; static const unsigned char test_text[] = "This is a test.\n"; @@ -49,7 +57,7 @@ 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((uintptr_t)bad_stack); + 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; @@ -67,14 +75,14 @@ static noinline void do_usercopy_stack(bool to_user, bool bad_frame) if (to_user) { pr_info("attempting good copy_to_user of local stack\n"); if (copy_to_user((void __user *)user_addr, good_stack, - sizeof(good_stack))) { + unconst + sizeof(good_stack))) { pr_warn("copy_to_user failed unexpectedly?!\n"); goto free_user; } pr_info("attempting bad copy_to_user of distant stack\n"); if (copy_to_user((void __user *)user_addr, bad_stack, - sizeof(good_stack))) { + unconst + sizeof(good_stack))) { pr_warn("copy_to_user failed, but lacked Oops\n"); goto free_user; } @@ -88,14 +96,14 @@ static noinline void do_usercopy_stack(bool to_user, bool bad_frame) pr_info("attempting good copy_from_user of local stack\n"); if (copy_from_user(good_stack, (void __user *)user_addr, - sizeof(good_stack))) { + unconst + sizeof(good_stack))) { pr_warn("copy_from_user failed unexpectedly?!\n"); goto free_user; } pr_info("attempting bad copy_from_user of distant stack\n"); if (copy_from_user(bad_stack, (void __user *)user_addr, - sizeof(good_stack))) { + unconst + sizeof(good_stack))) { pr_warn("copy_from_user failed, but lacked Oops\n"); goto free_user; } @@ -109,7 +117,7 @@ static void do_usercopy_heap_size(bool to_user) { unsigned long user_addr; unsigned char *one, *two; - const size_t size = 1024; + size_t size = unconst + 1024; one = kmalloc(size, GFP_KERNEL); two = kmalloc(size, GFP_KERNEL); @@ -285,13 +293,14 @@ void lkdtm_USERCOPY_KERNEL(void) pr_info("attempting good copy_to_user from kernel rodata\n"); if (copy_to_user((void __user *)user_addr, test_text, - sizeof(test_text))) { + unconst + sizeof(test_text))) { pr_warn("copy_to_user failed unexpectedly?!\n"); goto free_user; } pr_info("attempting bad copy_to_user from kernel text\n"); - if (copy_to_user((void __user *)user_addr, vm_mmap, PAGE_SIZE)) { + if (copy_to_user((void __user *)user_addr, vm_mmap, + unconst + PAGE_SIZE)) { pr_warn("copy_to_user failed, but lacked Oops\n"); goto free_user; } |