The patch titled
Subject: lkdtm: disable KASAN for rodata.o
has been removed from the -mm tree. Its filename was
lkdtm-disable-kasan-for-rodatao.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Marco Elver <elver@xxxxxxxxxx>
Subject: lkdtm: disable KASAN for rodata.o
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@xxxxxxxxxx
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/misc/lkdtm/Makefile | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/misc/lkdtm/Makefile~lkdtm-disable-kasan-for-rodatao
+++ a/drivers/misc/lkdtm/Makefile
@@ -11,6 +11,7 @@ lkdtm-$(CONFIG_LKDTM) += usercopy.o
lkdtm-$(CONFIG_LKDTM) += stackleak.o
lkdtm-$(CONFIG_LKDTM) += cfi.o
+KASAN_SANITIZE_rodata.o := n
KASAN_SANITIZE_stackleak.o := n
KCOV_INSTRUMENT_rodata.o := n
_
Patches currently in -mm which might be from elver@xxxxxxxxxx are
mm-add-kernel-electric-fence-infrastructure-fix.patch
mm-add-kernel-electric-fence-infrastructure-fix-2.patch
arm64-kfence-enable-kfence-for-arm64.patch
kfence-use-pt_regs-to-generate-stack-trace-on-faults.patch
kfence-documentation-add-kfence-documentation.patch
kfence-add-test-suite.patch
maintainers-add-entry-for-kfence.patch
