From a8f0b1f8ef628bd1003eed650862836e97b89fdd Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 23 Jul 2025 22:50:28 -0700 Subject: [PATCH] kstack_erase: Support Clang stack depth tracking Wire up CONFIG_KSTACK_ERASE to Clang 21's new stack depth tracking callback[1] option. Link: https://clang.llvm.org/docs/SanitizerCoverage.html#tracing-stack-depth [1] Acked-by: Nicolas Schier Link: https://lore.kernel.org/r/20250724055029.3623499-4-kees@kernel.org Signed-off-by: Kees Cook --- scripts/Makefile.kstack_erase | 6 ++++++ security/Kconfig.hardening | 5 ++++- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/scripts/Makefile.kstack_erase b/scripts/Makefile.kstack_erase index 5223d3a358172..c7bc2379e1133 100644 --- a/scripts/Makefile.kstack_erase +++ b/scripts/Makefile.kstack_erase @@ -8,6 +8,12 @@ kstack-erase-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK_VERBOSE) += -fplugin-arg-stack DISABLE_KSTACK_ERASE := -fplugin-arg-stackleak_plugin-disable endif +ifdef CONFIG_CC_IS_CLANG +kstack-erase-cflags-y += -fsanitize-coverage=stack-depth +kstack-erase-cflags-y += -fsanitize-coverage-stack-depth-callback-min=$(CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE) +DISABLE_KSTACK_ERASE := -fno-sanitize-coverage=stack-depth +endif + KSTACK_ERASE_CFLAGS := $(kstack-erase-cflags-y) export STACKLEAK_CFLAGS DISABLE_KSTACK_ERASE diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening index f7aa2024ab25f..b9a5bc3430aa2 100644 --- a/security/Kconfig.hardening +++ b/security/Kconfig.hardening @@ -82,10 +82,13 @@ choice endchoice +config CC_HAS_SANCOV_STACK_DEPTH_CALLBACK + def_bool $(cc-option,-fsanitize-coverage-stack-depth-callback-min=1) + config KSTACK_ERASE bool "Poison kernel stack before returning from syscalls" depends on HAVE_ARCH_KSTACK_ERASE - depends on GCC_PLUGINS + depends on GCC_PLUGINS || CC_HAS_SANCOV_STACK_DEPTH_CALLBACK help This option makes the kernel erase the kernel stack before returning from system calls. This has the effect of leaving -- 2.47.2