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=-19.4 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,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 74B91C433DB for ; Sun, 31 Jan 2021 21:14:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3142461492 for ; Sun, 31 Jan 2021 21:14:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229555AbhAaVKH (ORCPT ); Sun, 31 Jan 2021 16:10:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:57804 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231169AbhAaVDb (ORCPT ); Sun, 31 Jan 2021 16:03:31 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 09DFB64E3E; Sun, 31 Jan 2021 17:24:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612113893; bh=wyJOIMqfy6bpIafa5t0YFAYaqCcPgkGd3Ld8Ak0s+4g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GYMmUmNNSToSJ9gFwLv/mu6xNkgP035KUck5/33bz4STmHKwwtzm5mMabUnTtdZad vwNhHo26h8b4x9YRjQhy4R7MS+xTxK5IG0+Bdxs1QTnxQ5mmHKu6Q3Aob4iZfypiQk ULU19rz2g0VcuXiMEuCS4TBwOFyJMMnWpq76PI+h+uKGIQrRRrC6WIn3mDWwEDmVeu kEazVEk+4tQThEn2/W6LescJnukW4udMbxB4A9xg4cMt2CPzg3JDrZ7NMUXwvrkRGi IKhS21uU32A+YOiTw28j/Vv7xNrSx5CCPPd3Ew8i8t8PCfa3Ub9Sb4DO/WDla3AJd5 AvW+WkK0rqfeA== 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 08/11] x86/fault: Bypass no_context() for implicit kernel faults from usermode Date: Sun, 31 Jan 2021 09:24:39 -0800 Message-Id: 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 6f43d080e1e8..177b612c7f33 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -789,44 +789,49 @@ __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