On Thu, Jun 27, 2024 at 03:53:14PM +0800, Jinjie Ruan wrote: > > > On 2024/6/24 15:30, Linus Walleij wrote: > > On Mon, Jun 24, 2024 at 4:33 AM Jinjie Ruan <ruanjinjie@xxxxxxxxxx> 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@xxxxxxxxxx> > >> Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > > > > Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx> > > > > I was digging around to see if this would interfere with BPF > > trampolines, but the > > BPF code seems so generic that I assume it already takes stackleak into account. > > > Thank you very much, as Kees said, can this patch go via > rmk's patch tracker now? Probably yes (we have some reviews now). Please go ahead and add it there. -- Kees Cook
