Re: [PATCH v2 10/17] lkdtm: use __va_function
From: Nick Desaulniers <hidden>
Date: 2021-03-18 18:44:49
Also in:
bpf, linux-arm-kernel, linux-hardening, linux-kbuild, linux-pci, lkml
On Thu, Mar 18, 2021 at 10:11 AM Sami Tolvanen [off-list ref] wrote:
To ensure we take the actual address of a function in kernel text, use __va_function. 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.
Should patch 10 and 12 be reordered against one another? Otherwise it looks like 12 defines __va_function while 10 uses it?
quoted hunk ↗ jump to hunk
Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Kees Cook <redacted> --- drivers/misc/lkdtm/usercopy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c index 109e8d4302c1..d173d6175c87 100644 --- a/drivers/misc/lkdtm/usercopy.c +++ b/drivers/misc/lkdtm/usercopy.c@@ -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, __va_function(vm_mmap), unconst + PAGE_SIZE)) { pr_warn("copy_to_user failed, but lacked Oops\n"); goto free_user; --2.31.0.291.g576ba9dcdaf-goog
-- Thanks, ~Nick Desaulniers