Add the STACKLEAK gcc plugin to arm32 by adding the helper used by
stackleak common code: on_thread_stack(). It initialize the stack with the
poison value before returning from system calls which improves the kernel
security. Additionally, this disables the plugin in EFI stub code and
decompress code, which are out of scope for the protection.
Before the test on Qemu versatilepb board:
# echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT
lkdtm: Performing direct entry STACKLEAK_ERASING
lkdtm: XFAIL: stackleak is not supported on this arch (HAVE_ARCH_STACKLEAK=n)
After:
# echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT
lkdtm: Performing direct entry STACKLEAK_ERASING
lkdtm: stackleak stack usage:
high offset: 80 bytes
current: 280 bytes
lowest: 696 bytes
tracked: 696 bytes
untracked: 192 bytes
poisoned: 7220 bytes
low offset: 4 bytes
lkdtm: OK: the rest of the thread stack is properly erased
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
2335c9cb83