Re: [patch 01/18] powerpc: Move stack randomization after syscall_enter_from_user_mode()

Radu Rendec <[email protected]> Wed, 08 Jul 2026 13:22:58 -0400
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Message-ID <[email protected]> 
On Tue, 2026-07-07 at 21:05 +0200, Thomas Gleixner wrote:
> add_random_kstack_offset() is invoked before syscall_enter_from_user_mode=
()
> establishes state. That's wrong because add_random_kstack_offset() calls
> into instrumentable code.
>=20
> Move it after syscall_enter_from_user_mode() to ensure that state is
> correctly established.
>=20
> Signed-off-by: Thomas Gleixner <[email protected]>
> Cc: Michael Ellerman <[email protected]>
> Cc: Shrikanth Hegde <[email protected]>
> Cc: [email protected]
> ---
> =C2=A0arch/powerpc/kernel/syscall.c |=C2=A0=C2=A0=C2=A0 2 +-
> =C2=A01 file changed, 1 insertion(+), 1 deletion(-)
>=20
> --- a/arch/powerpc/kernel/syscall.c
> +++ b/arch/powerpc/kernel/syscall.c
> @@ -19,8 +19,8 @@ notrace long system_call_exception(struc
> =C2=A0	long ret;
> =C2=A0	syscall_fn f;
> =C2=A0
> -	add_random_kstack_offset();
> =C2=A0	r0 =3D syscall_enter_from_user_mode(regs, r0);
> +	add_random_kstack_offset();
> =C2=A0
> =C2=A0	if (unlikely(r0 >=3D NR_syscalls)) {
> =C2=A0		if (unlikely(trap_is_unsupported_scv(regs))) {

Reviewed-by: Radu Rendec <[email protected]>