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=unavailable 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 C4AF2C11F66 for ; Tue, 6 Jul 2021 19:06:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8C5A61C6D for ; Tue, 6 Jul 2021 19:06:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231713AbhGFTJI (ORCPT ); Tue, 6 Jul 2021 15:09:08 -0400 Received: from mga11.intel.com ([192.55.52.93]:6713 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230071AbhGFTJH (ORCPT ); Tue, 6 Jul 2021 15:09:07 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10037"; a="206166879" X-IronPort-AV: E=Sophos;i="5.83,329,1616482800"; d="scan'208";a="206166879" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jul 2021 12:06:27 -0700 X-IronPort-AV: E=Sophos;i="5.83,329,1616482800"; d="scan'208";a="427687576" Received: from agluck-desk2.sc.intel.com ([10.3.52.146]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jul 2021 12:06:26 -0700 From: Tony Luck To: Borislav Petkov Cc: Tony Luck , Ding Hui , naoya.horiguchi@nec.com, osalvador@suse.de, Youquan Song , huangcun@sangfor.com.cn, x86@kernel.org, linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/3] x86/mce: Change to not send SIGBUS error during copy from user Date: Tue, 6 Jul 2021 12:06:18 -0700 Message-Id: <20210706190620.1290391-2-tony.luck@intel.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210706190620.1290391-1-tony.luck@intel.com> References: <20210706190620.1290391-1-tony.luck@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index 22791aadc085..dd03971e5ad5 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -1265,7 +1265,7 @@ static void kill_me_maybe(struct callback_head *cb) flags |= MF_MUST_KILL; ret = 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; @@ -1279,25 +1279,27 @@ static void kill_me_maybe(struct callback_head *cb) if (ret == -EHWPOISON) return; - if (p->mce_vaddr != (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 = container_of(cb, struct task_struct, mce_kill_me); + + 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); } -static void queue_task_work(struct mce *m, int kill_current_task) +static void queue_task_work(struct mce *m, void (*func)(struct callback_head *)) { current->mce_addr = m->addr; current->mce_kflags = m->kflags; current->mce_ripv = !!(m->mcgstatus & MCG_STATUS_RIPV); current->mce_whole_page = whole_page(m); - if (kill_current_task) - current->mce_kill_me.func = kill_me_now; - else - current->mce_kill_me.func = kill_me_maybe; + current->mce_kill_me.func = func; task_work_add(current, ¤t->mce_kill_me, TWA_RESUME); } @@ -1435,7 +1437,10 @@ 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)); - queue_task_work(&m, kill_current_task); + if (kill_current_task) + queue_task_work(&m, kill_me_now); + else + queue_task_work(&m, kill_me_maybe); } else { /* @@ -1453,7 +1458,7 @@ noinstr void do_machine_check(struct pt_regs *regs) } if (m.kflags & MCE_IN_KERNEL_COPYIN) - queue_task_work(&m, kill_current_task); + queue_task_work(&m, kill_me_never); } out: mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); -- 2.29.2