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@xxxxxxxxxx> --- arch/riscv/Kconfig | 1 + arch/riscv/kernel/entry.S | 4 ++++ drivers/firmware/efi/libstub/Makefile | 3 ++- 3 files changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 0525ee2d63c7..9cbfdffec96c 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -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 diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 68a24cf9481a..80ff55a26d13 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -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) diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index 06f0428a723c..3a9521c57641 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -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 -- 2.43.0
