From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.mindbit.ro (xs1.mindbit.ro [80.86.107.70]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D9BA7423142; Wed, 8 Jul 2026 17:23:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.86.107.70 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783531427; cv=none; b=fxH8cldDHZ2J+6U6UuC12FwBl/8w5AZNzm/ewymhoUSjZtyb/S9uqmpTaDcOO5Hf11YX9fSmPJsxaaFmVw+NKpHb/op9BTzhuAHfPegkjN2xokvOtmtqEuFPcouIyyw923ntWuDKfcJioH1KgvulexJQhZTG3qtjNqVICObLNOc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783531427; c=relaxed/simple; bh=2FwtfvgYnqfApEQzRk2DFogg7eg5G8hQUvc99OfH2ig=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=b84SP7LnmZcj0+jcfb0cw9vrmMWRLuZLnB0EYoTvn7/D96LnTgNWcHIAdHnoCn34FVCLV/L0Ta6yE4VIHBuRq2KRS3HMFdZ6jSDVv2faCNhMYA++jS8aUxw7Dv2DygkLMHlA1Z5Nw3Y7NPTXkXHa8OB08DRg+LH8S0kidtg8Qas= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=rendec.net; spf=pass smtp.mailfrom=rendec.net; dkim=pass (2048-bit key) header.d=rendec.net header.i=@rendec.net header.b=MwinUj84; arc=none smtp.client-ip=80.86.107.70 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=rendec.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rendec.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=rendec.net header.i=@rendec.net header.b="MwinUj84" Received: from bat.kanata.rendec.net (unknown [24.114.111.125]) by mail.mindbit.ro (Postfix) with ESMTPSA id C6722C2A01; Wed, 8 Jul 2026 20:23:07 +0300 (EEST) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.mindbit.ro C6722C2A01 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rendec.net; s=default; t=1783531415; bh=Z81AqF8sZ0HbKd4OyTLskHjABuyT0Tc0putXPru6w9M=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=MwinUj84iH00nexlmnhmDgR8X+WQik+DrvADedzcPZ9CeQY6xX1Fx3GoyEAx9wrw+ Qdscs2HlxOLAQsUWmM9C8f5DrkHkoVgKYwJs+XQ2tFPd5t4en+6vUqgSLYxSBdIwBj 555LvdKRH7m1aCTa5jMD6siDGQdvrKp961ZSe90G1chGvdgdtY0LoAvKa+i9v8wU5c bWRF7OLablSVqprq4HLnjHYPD0Doh6wC1fnDaN+ZveYxw8RUEs8Ut6dFJfZDIKl5We w78c65fWXzE8Q1+/ZRaJSLn4ncOl+TKAdXUve5QtEGG7DQ85WMF0AHi0oAnduE4Xgt l68qBKty9jNkA== Message-ID: <4614d1281cace737e3e117bd7242253475a30f58.camel@rendec.net> Subject: Re: [patch 01/18] powerpc: Move stack randomization after syscall_enter_from_user_mode() From: Radu Rendec To: Thomas Gleixner , LKML Cc: Peter Zijlstra , Michael Ellerman , Shrikanth Hegde , linuxppc-dev@lists.ozlabs.org, Kees Cook , Huacai Chen , loongarch@lists.linux.dev, Paul Walmsley , Palmer Dabbelt , linux-riscv@lists.infradead.org, Sven Schnelle , linux-s390@vger.kernel.org, x86@kernel.org, Mark Rutland , Jinjie Ruan , Andy Lutomirski , Oleg Nesterov , Richard Henderson , Russell King , Catalin Marinas , Guo Ren , Geert Uytterhoeven , Thomas Bogendoerfer , Helge Deller , Yoshinori Sato , Richard Weinberger , Chris Zankel , linux-arm-kernel@lists.infradead.org, linux-alpha@vger.kernel.org, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-sh@vger.kernel.org, linux-um@lists.infradead.org, Arnd Bergmann , Vineet Gupta , Will Deacon , Brian Cain , Michal Simek , Dinh Nguyen , "David S. Miller" , Andreas Larsson , linux-snps-arc@lists.infradead.org, linux-hexagon@vger.kernel.org, linux-openrisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, Michal =?ISO-8859-1?Q?Such=E1nek?= , Jonathan Corbet , linux-doc@vger.kernel.org Date: Wed, 08 Jul 2026 13:22:58 -0400 In-Reply-To: <20260707190253.718191130@kernel.org> References: <20260707181957.433213175@kernel.org> <20260707190253.718191130@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 > Cc: Michael Ellerman > Cc: Shrikanth Hegde > Cc: linuxppc-dev@lists.ozlabs.org > --- > =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