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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,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 E8C61C432BE for ; Wed, 18 Aug 2021 00:29:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 96E8661042 for ; Wed, 18 Aug 2021 00:29:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 96E8661042 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id C30F0900005; Tue, 17 Aug 2021 20:29:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B9476900004; Tue, 17 Aug 2021 20:29:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 96E8A900003; Tue, 17 Aug 2021 20:29:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0244.hostedemail.com [216.40.44.244]) by kanga.kvack.org (Postfix) with ESMTP id 772F3900002 for ; Tue, 17 Aug 2021 20:29:56 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 3447F1CFCC for ; Wed, 18 Aug 2021 00:29:56 +0000 (UTC) X-FDA: 78486318792.10.DE2DB5A Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by imf11.hostedemail.com (Postfix) with ESMTP id A3146F000584 for ; Wed, 18 Aug 2021 00:29:55 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10079"; a="216260725" X-IronPort-AV: E=Sophos;i="5.84,330,1620716400"; d="scan'208";a="216260725" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Aug 2021 17:29:52 -0700 X-IronPort-AV: E=Sophos;i="5.84,330,1620716400"; d="scan'208";a="520687345" Received: from agluck-desk2.sc.intel.com ([10.3.52.146]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Aug 2021 17:29:52 -0700 From: Tony Luck To: Borislav Petkov Cc: Jue Wang , Ding Hui , naoya.horiguchi@nec.com, osalvador@suse.de, Youquan Song , huangcun@sangfor.com.cn, x86@kernel.org, linux-edac@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Tony Luck Subject: [PATCH v2 2/3] x86/mce: Change to not send SIGBUS error during copy from user Date: Tue, 17 Aug 2021 17:29:41 -0700 Message-Id: <20210818002942.1607544-3-tony.luck@intel.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210818002942.1607544-1-tony.luck@intel.com> References: <20210706190620.1290391-1-tony.luck@intel.com> <20210818002942.1607544-1-tony.luck@intel.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: A3146F000584 Authentication-Results: imf11.hostedemail.com; dkim=none; spf=none (imf11.hostedemail.com: domain of tony.luck@intel.com has no SPF policy when checking 134.134.136.65) smtp.mailfrom=tony.luck@intel.com; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=intel.com (policy=none) X-Rspamd-Server: rspam01 X-Stat-Signature: znyw1mr4iaoc8oxgwi1j4cdyeodycyhg X-HE-Tag: 1629246595-578465 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Sending a SIGBUS for a copy from user is not the correct semantic. System calls should return -EFAULT (or a short count for write(2)). Signed-off-by: Tony Luck --- arch/x86/kernel/cpu/mce/core.c | 35 +++++++++++++++++++--------------- 1 file changed, 20 insertions(+), 15 deletions(-) diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/cor= e.c index 94830ee9581c..957ec60cd2a8 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -1269,7 +1269,7 @@ static void kill_me_maybe(struct callback_head *cb) flags |=3D MF_MUST_KILL; =20 ret =3D memory_failure(p->mce_addr >> PAGE_SHIFT, flags); - if (!ret && !(p->mce_kflags & MCE_IN_KERNEL_COPYIN)) { + if (!ret) { set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page); sync_core(); return; @@ -1283,15 +1283,21 @@ static void kill_me_maybe(struct callback_head *c= b) if (ret =3D=3D -EHWPOISON) return; =20 - if (p->mce_vaddr !=3D (void __user *)-1l) { - force_sig_mceerr(BUS_MCEERR_AR, p->mce_vaddr, PAGE_SHIFT); - } else { - pr_err("Memory error not recovered"); - kill_me_now(cb); - } + pr_err("Memory error not recovered"); + kill_me_now(cb); +} + +static void kill_me_never(struct callback_head *cb) +{ + struct task_struct *p =3D container_of(cb, struct task_struct, mce_kill= _me); + + p->mce_count =3D 0; + pr_err("Kernel accessed poison in user space at %llx\n", p->mce_addr); + if (!memory_failure(p->mce_addr >> PAGE_SHIFT, 0)) + set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page); } =20 -static void queue_task_work(struct mce *m, char *msg, int kill_current_t= ask) +static void queue_task_work(struct mce *m, char *msg, void (*func)(struc= t callback_head *)) { int count =3D ++current->mce_count; =20 @@ -1301,11 +1307,7 @@ static void queue_task_work(struct mce *m, char *m= sg, int kill_current_task) current->mce_kflags =3D m->kflags; current->mce_ripv =3D !!(m->mcgstatus & MCG_STATUS_RIPV); current->mce_whole_page =3D whole_page(m); - - if (kill_current_task) - current->mce_kill_me.func =3D kill_me_now; - else - current->mce_kill_me.func =3D kill_me_maybe; + current->mce_kill_me.func =3D func; } =20 /* Ten is likley overkill. Don't expect more than two faults before tas= k_work() */ @@ -1456,7 +1458,10 @@ noinstr void do_machine_check(struct pt_regs *regs= ) /* If this triggers there is no way to recover. Die hard. */ BUG_ON(!on_thread_stack() || !user_mode(regs)); =20 - queue_task_work(&m, msg, kill_current_task); + if (kill_current_task) + queue_task_work(&m, msg, kill_me_now); + else + queue_task_work(&m, msg, kill_me_maybe); =20 } else { /* @@ -1474,7 +1479,7 @@ noinstr void do_machine_check(struct pt_regs *regs) } =20 if (m.kflags & MCE_IN_KERNEL_COPYIN) - queue_task_work(&m, msg, kill_current_task); + queue_task_work(&m, msg, kill_me_never); } out: mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); --=20 2.29.2