UPSTREAM: lkdtm: disable KASAN for rodata.o
[ Upstream commit 6d5a88cd0c1506115d71a4d3a26b60645c89df6c ]
Building lkdtm with KASAN and Clang 11 or later results in the following
error when attempting to load the module:
kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
BUG: unable to handle page fault for address: ffffffffc019cd70
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0011) - permissions violation
...
RIP: 0010:asan.module_ctor+0x0/0xffffffffffffa290 [lkdtm]
...
Call Trace:
do_init_module+0x17c/0x570
load_module+0xadee/0xd0b0
__x64_sys_finit_module+0x16c/0x1a0
do_syscall_64+0x34/0x50
entry_SYSCALL_64_after_hwframe+0x44/0xa9
The reason is that rodata.o generates a dummy function that lives in
.rodata to validate that .rodata can't be executed; however, Clang 11 adds
KASAN globals support by generating module constructors to initialize
globals redzones. When Clang 11 adds a module constructor to rodata.o, it
is also added to .rodata: any attempt to call it on initialization results
in the above error.
Therefore, disable KASAN instrumentation for rodata.o.
Link: https://lkml.kernel.org/r/20201214191413.3164796-1-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Bug: 172318110
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Change-Id: I0a3662322bac8961b0f87ab5e8e87acfb1ac3ec5
diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile
index dd4c936..53af7c2 100644
--- a/drivers/misc/lkdtm/Makefile
+++ b/drivers/misc/lkdtm/Makefile
@@ -11,6 +11,7 @@
lkdtm-$(CONFIG_LKDTM) += stackleak.o
lkdtm-$(CONFIG_LKDTM) += cfi.o
+KASAN_SANITIZE_rodata.o := n
KASAN_SANITIZE_stackleak.o := n
KCOV_INSTRUMENT_rodata.o := n
CFLAGS_REMOVE_rodata.o += $(CC_FLAGS_LTO)