Re: [PATCH v2] ARM: Add support for STACKLEAK gcc plugin

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Mon, Jul 22, 2024 at 10:53:10AM +0800, Jinjie Ruan wrote:
> Gentle ping.
> 
> On 2024/6/24 10:36, Jinjie Ruan wrote:
> > 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>

Is this a feature that you have a use case for?

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