configs/hardening: Enable CONFIG_KSTACK_ERASE

Since we can wipe the stack with both Clang and GCC plugins, enable this
for the "hardening.config" for wider testing.

Link: https://lore.kernel.org/r/20250717232519.2984886-12-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>

diff --git a/kernel/configs/hardening.config b/kernel/configs/hardening.config
index dd7c32fb5ac1bc72097ccd171a2cff2f0abe9b23..d24c2772d04d7f7444b04084c8764d95735b5b87 100644 (file)
--- a/kernel/configs/hardening.config
+++ b/kernel/configs/hardening.config
@@ -63,6 +63,9 @@ CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y
 # Initialize all stack variables to zero on function entry.
 CONFIG_INIT_STACK_ALL_ZERO=y
 
+# Wipe kernel stack after syscall completion to reduce stale data lifetime.
+CONFIG_KSTACK_ERASE=y
+
 # Wipe RAM at reboot via EFI. For more details, see:
 # https://trustedcomputinggroup.org/resource/pc-client-work-group-platform-reset-attack-mitigation-specification/
 # https://bugzilla.redhat.com/show_bug.cgi?id=1532058