lkml.org 
[lkml]   [2021]   [Mar]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
Subject[PATCH v4 10/17] lkdtm: use function_nocfi
From
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: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
---
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..15d220ef35a5 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, function_nocfi(vm_mmap),
unconst + PAGE_SIZE)) {
pr_warn("copy_to_user failed, but lacked Oops\n");
goto free_user;
--
2.31.0.291.g576ba9dcdaf-goog
\
 
 \ /
  Last update: 2021-03-31 23:29    [W:0.064 / U:0.488 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site