From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1CC69C433B4 for ; Fri, 16 Apr 2021 12:33:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F3AC4611AC for ; Fri, 16 Apr 2021 12:33:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235345AbhDPMdw (ORCPT ); Fri, 16 Apr 2021 08:33:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:60602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234291AbhDPMdv (ORCPT ); Fri, 16 Apr 2021 08:33:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 67EF2610E6; Fri, 16 Apr 2021 12:33:25 +0000 (UTC) Date: Fri, 16 Apr 2021 13:33:22 +0100 From: Catalin Marinas To: He Zhe Cc: oleg@redhat.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, paul@paul-moore.com, eparis@redhat.com, linux-audit@redhat.com, linux-kernel@vger.kernel.org, Mark Rutland Subject: Re: [PATCH 1/3] arm64: ptrace: Add is_syscall_success to handle compat Message-ID: <20210416123322.GA23184@arm.com> References: <20210416075533.7720-1-zhe.he@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210416075533.7720-1-zhe.he@windriver.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 16, 2021 at 03:55:31PM +0800, He Zhe wrote: > The general version of is_syscall_success does not handle 32-bit > compatible case, which would cause 32-bit negative return code to be > recoganized as a positive number later and seen as a "success". > > Since is_compat_thread is defined in compat.h, implementing > is_syscall_success in ptrace.h would introduce build failure due to > recursive inclusion of some basic headers like mutex.h. We put the > implementation to ptrace.c > > Signed-off-by: He Zhe > --- > arch/arm64/include/asm/ptrace.h | 3 +++ > arch/arm64/kernel/ptrace.c | 10 ++++++++++ > 2 files changed, 13 insertions(+) > > diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h > index e58bca832dff..3c415e9e5d85 100644 > --- a/arch/arm64/include/asm/ptrace.h > +++ b/arch/arm64/include/asm/ptrace.h > @@ -328,6 +328,9 @@ static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc) > regs->regs[0] = rc; > } > > +extern inline int is_syscall_success(struct pt_regs *regs); > +#define is_syscall_success(regs) is_syscall_success(regs) > + > /** > * regs_get_kernel_argument() - get Nth function argument in kernel > * @regs: pt_regs of that context > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > index 170f42fd6101..3266201f8c60 100644 > --- a/arch/arm64/kernel/ptrace.c > +++ b/arch/arm64/kernel/ptrace.c > @@ -1909,3 +1909,13 @@ int valid_user_regs(struct user_pt_regs *regs, struct task_struct *task) > else > return valid_native_regs(regs); > } > + > +inline int is_syscall_success(struct pt_regs *regs) > +{ > + unsigned long val = regs->regs[0]; > + > + if (is_compat_thread(task_thread_info(current))) > + val = sign_extend64(val, 31); > + > + return !IS_ERR_VALUE(val); > +} It's better to use compat_user_mode(regs) here instead of is_compat_thread(). It saves us from worrying whether regs are for the current context. I think we should change regs_return_value() instead. This function seems to be called from several other places and it has the same potential problems if called on compat pt_regs. -- Catalin