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=-19.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 0D560C433E0 for ; Wed, 10 Feb 2021 02:43:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CA07264E4E for ; Wed, 10 Feb 2021 02:43:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235428AbhBJCml (ORCPT ); Tue, 9 Feb 2021 21:42:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:34656 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235107AbhBJCge (ORCPT ); Tue, 9 Feb 2021 21:36:34 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id EB8A864E79; Wed, 10 Feb 2021 02:33:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612924437; bh=y/dOirvG5AtLV2tIfLLxXk9twm9gXZqV5HopLGhImfI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TSSwq/4JBgfQT7OHlfplL7hzYMFUP4FHqvCbQaLsTQtvT65Bdrx2UqVAavWAGOMyW W5L/yTEjjKqN2O2KlVAV2YmJRrIuPFcTLq6EtEwodw23MWp6w9v0xS4jQT1wqINE3D 03YIVGWh+bnOio+1p/hco8DVbo4CnjBsdWrufd4fQB6s8W4as3bu5edeV+bhZqz66z SzeVXFwqru4j6+oIAJrXj6bol4F6PEXglxV/P9jk4ITK7DtxbtFRPD0mcGw6VyMBQs 5/Kuox1LRBAi9wDyi7D+7hvx8NEz4eAkPySxACUkF4zAmp/q99ygtNw52gpEydVRic CmMLZD/fhCo8Q== From: Andy Lutomirski To: x86@kernel.org Cc: LKML , Dave Hansen , Alexei Starovoitov , Daniel Borkmann , Yonghong Song , Masami Hiramatsu , Andy Lutomirski , Peter Zijlstra Subject: [PATCH v2 10/14] x86/fault: Bypass no_context() for implicit kernel faults from usermode Date: Tue, 9 Feb 2021 18:33:42 -0800 Message-Id: <6e3d1129494a8de1e59d28012286e3a292a2296e.1612924255.git.luto@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We can drop an indentation level and remove the last user_mode(regs) == true caller of no_context() by directly OOPSing for implicit kernel faults from usermode. Cc: Dave Hansen Cc: Peter Zijlstra Signed-off-by: Andy Lutomirski --- arch/x86/mm/fault.c | 59 ++++++++++++++++++++++++--------------------- 1 file changed, 32 insertions(+), 27 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 8b8bd0a4f4b2..f735639455a5 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -825,44 +825,49 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, { struct task_struct *tsk = current; - /* User mode accesses just cause a SIGSEGV */ - if (user_mode(regs) && (error_code & X86_PF_USER)) { - /* - * It's possible to have interrupts off here: - */ - local_irq_enable(); + if (!user_mode(regs)) { + no_context(regs, error_code, address, pkey, si_code); + return; + } - /* - * Valid to do another page fault here because this one came - * from user space: - */ - if (is_prefetch(regs, error_code, address)) - return; + if (!(error_code & X86_PF_USER)) { + /* Implicit user access to kernel memory -- just oops */ + page_fault_oops(regs, error_code, address); + return; + } - if (is_errata100(regs, address)) - return; + /* + * User mode accesses just cause a SIGSEGV. + * It's possible to have interrupts off here: + */ + local_irq_enable(); - sanitize_error_code(address, &error_code); + /* + * Valid to do another page fault here because this one came + * from user space: + */ + if (is_prefetch(regs, error_code, address)) + return; - if (fixup_vdso_exception(regs, X86_TRAP_PF, error_code, address)) - return; + if (is_errata100(regs, address)) + return; - if (likely(show_unhandled_signals)) - show_signal_msg(regs, error_code, address, tsk); + sanitize_error_code(address, &error_code); - set_signal_archinfo(address, error_code); + if (fixup_vdso_exception(regs, X86_TRAP_PF, error_code, address)) + return; - if (si_code == SEGV_PKUERR) - force_sig_pkuerr((void __user *)address, pkey); + if (likely(show_unhandled_signals)) + show_signal_msg(regs, error_code, address, tsk); - force_sig_fault(SIGSEGV, si_code, (void __user *)address); + set_signal_archinfo(address, error_code); - local_irq_disable(); + if (si_code == SEGV_PKUERR) + force_sig_pkuerr((void __user *)address, pkey); - return; - } + force_sig_fault(SIGSEGV, si_code, (void __user *)address); - no_context(regs, error_code, address, SIGSEGV, si_code); + local_irq_disable(); } static noinline void -- 2.29.2