@@ -118,6 +118,7 @@ config RISCV
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
select HAVE_ARCH_SECCOMP_FILTER
+ select HAVE_ARCH_STACKLEAK
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU
@@ -10,6 +10,7 @@
#include <asm/page.h>
#include <linux/const.h>
+#include <linux/sizes.h>
/* thread information allocation */
#define THREAD_SIZE_ORDER CONFIG_THREAD_SIZE_ORDER
@@ -130,6 +130,10 @@ SYM_CODE_START_NOALIGN(ret_from_exception)
#endif
bnez s0, 1f
+#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
+ call stackleak_erase_on_task_stack
+#endif
+
/* Save unwound kernel stack pointer in thread_info */
addi s0, sp, PT_SIZE_ON_STACK
REG_S s0, TASK_TI_KERNEL_SP(tp)
@@ -28,7 +28,8 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
-DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
-DEFI_HAVE_STRCMP -fno-builtin -fpic \
$(call cc-option,-mno-single-pic-base)
-cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
+cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax \
+ $(DISABLE_STACKLEAK_PLUGIN)
cflags-$(CONFIG_LOONGARCH) += -fpie
cflags-$(CONFIG_EFI_PARAMS_FROM_FDT) += -I$(srctree)/scripts/dtc/libfdt
Add support for the stackleak feature. Whenever the kernel returns to user space the kernel stack is filled with a poison value. At the same time, disables the plugin in EFI stub code because EFI stub is out of scope for the protection. Tested on qemu and milkv duo: / # echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT [ 38.675575] lkdtm: Performing direct entry STACKLEAK_ERASING [ 38.678448] lkdtm: stackleak stack usage: [ 38.678448] high offset: 288 bytes [ 38.678448] current: 496 bytes [ 38.678448] lowest: 1328 bytes [ 38.678448] tracked: 1328 bytes [ 38.678448] untracked: 448 bytes [ 38.678448] poisoned: 14312 bytes [ 38.678448] low offset: 8 bytes [ 38.689887] lkdtm: OK: the rest of the thread stack is properly erased Signed-off-by: Jisheng Zhang <jszhang@kernel.org> --- since v2: - add #include <linux/sizes.h> to fixing compiler error found by Charlie arch/riscv/Kconfig | 1 + arch/riscv/include/asm/thread_info.h | 1 + arch/riscv/kernel/entry.S | 4 ++++ drivers/firmware/efi/libstub/Makefile | 3 ++- 4 files changed, 8 insertions(+), 1 deletion(-)