diff mbox series

[v5,08/15] lkdtm: Use an opaque type for lkdtm_rodata_do_nothing

Message ID 20211013181658.1020262-9-samitolvanen@google.com (mailing list archive)
State Changes Requested
Headers show
Series x86: Add support for Clang CFI | expand

Commit Message

Sami Tolvanen Oct. 13, 2021, 6:16 p.m. UTC 
Use an opaque type for lkdtm_rodata_do_nothing to stop the compiler
from generating a CFI jump table entry that jumps to .rodata.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
---
 drivers/misc/lkdtm/lkdtm.h  | 2 +-
 drivers/misc/lkdtm/perms.c  | 2 +-
 drivers/misc/lkdtm/rodata.c | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h
index c212a253edde..35535c422939 100644
--- a/drivers/misc/lkdtm/lkdtm.h
+++ b/drivers/misc/lkdtm/lkdtm.h
@@ -137,7 +137,7 @@  void lkdtm_REFCOUNT_TIMING(void);
 void lkdtm_ATOMIC_TIMING(void);
 
 /* rodata.c */
-void lkdtm_rodata_do_nothing(void);
+DECLARE_NOT_CALLED_FROM_C(lkdtm_rodata_do_nothing);
 
 /* usercopy.c */
 void __init lkdtm_usercopy_init(void);
diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c
index 2dede2ef658f..fa2bd90bd8ee 100644
--- a/drivers/misc/lkdtm/perms.c
+++ b/drivers/misc/lkdtm/perms.c
@@ -151,7 +151,7 @@  void lkdtm_EXEC_VMALLOC(void)
 
 void lkdtm_EXEC_RODATA(void)
 {
-	execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS);
+	execute_location((void *)lkdtm_rodata_do_nothing, CODE_AS_IS);
 }
 
 void lkdtm_EXEC_USERSPACE(void)
diff --git a/drivers/misc/lkdtm/rodata.c b/drivers/misc/lkdtm/rodata.c
index baacb876d1d9..17ed0ad4e6ae 100644
--- a/drivers/misc/lkdtm/rodata.c
+++ b/drivers/misc/lkdtm/rodata.c
@@ -3,7 +3,7 @@ 
  * This includes functions that are meant to live entirely in .rodata
  * (via objcopy tricks), to validate the non-executability of .rodata.
  */
-#include "lkdtm.h"
+void lkdtm_rodata_do_nothing(void);
 
 void noinstr lkdtm_rodata_do_nothing(void)
 {