Commit 6c4df54e authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Kees Cook
Browse files

lkdtm: use function_nocfi 



To ensure we take the actual address of a function in kernel text,
use function_nocfi. Otherwise, with CONFIG_CFI_CLANG, the compiler
replaces the address with a pointer to the CFI jump table, which is
actually in the module when compiled with CONFIG_LKDTM=m.

Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Tested-by: default avatarNathan Chancellor <nathan@kernel.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210408182843.1754385-11-samitolvanen@google.com
parent 4f0f586b

drivers/misc/lkdtm/usercopy.c

+1 −1
Original line number Diff line number Diff line
@@ -314,7 +314,7 @@ void lkdtm_USERCOPY_KERNEL(void) 


	pr_info("attempting bad copy_to_user from kernel text: %px\n",

		vm_mmap);

	if (copy_to_user((void __user *)user_addr, vm_mmap,

	if (copy_to_user((void __user *)user_addr, function_nocfi(vm_mmap),

			 unconst + PAGE_SIZE)) {

		pr_warn("copy_to_user failed, but lacked Oops\n");

		goto free_user;