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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DA47EC3DA64 for ; Tue, 6 Aug 2024 06:13:17 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4WdNK84LkLz3d3Q for ; Tue, 6 Aug 2024 16:13:16 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=huawei.com (client-ip=45.249.212.189; helo=szxga03-in.huawei.com; envelope-from=ruanjinjie@huawei.com; receiver=lists.ozlabs.org) Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4WdNJg63f9z3cG5 for ; Tue, 6 Aug 2024 16:12:46 +1000 (AEST) Received: from mail.maildlp.com (unknown [172.19.163.174]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4WdNCH54YVzQp91; Tue, 6 Aug 2024 14:08:11 +0800 (CST) Received: from kwepemi100008.china.huawei.com (unknown [7.221.188.57]) by mail.maildlp.com (Postfix) with ESMTPS id 1B2B014022E; Tue, 6 Aug 2024 14:12:37 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by kwepemi100008.china.huawei.com (7.221.188.57) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Tue, 6 Aug 2024 14:12:35 +0800 Message-ID: Date: Tue, 6 Aug 2024 14:12:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH v5.10] powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt. Content-Language: en-US To: Michael Ellerman , , , , , , , , , , References: <20240805114544.1552341-1-ruanjinjie@huawei.com> <87frrii66q.fsf@mail.lhotse> From: Jinjie Ruan In-Reply-To: <87frrii66q.fsf@mail.lhotse> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.109.254] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemi100008.china.huawei.com (7.221.188.57) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 2024/8/6 13:14, Michael Ellerman wrote: > Hi Jinjie Ruan, > > If you want to submit this as a stable backport you need to send it > To: stable@vger.kernel.org. > > Jinjie Ruan writes: >> From: Mahesh Salgaonkar > > Although it's somewhat modified, this is still a backport of an upstream > commit, so it should include the following line: > > [ Upstream commit 0db880fc865ffb522141ced4bfa66c12ab1fbb70 ] Thank you very much! I'll resend it. > >> nmi_enter()/nmi_exit() touches per cpu variables which can lead to kernel >> crash when invoked during real mode interrupt handling (e.g. early HMI/MCE >> interrupt handler) if percpu allocation comes from vmalloc area. >> >> Early HMI/MCE handlers are called through DEFINE_INTERRUPT_HANDLER_NMI() >> wrapper which invokes nmi_enter/nmi_exit calls. We don't see any issue when >> percpu allocation is from the embedded first chunk. However with >> CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpu >> allocation can come from the vmalloc area. >> >> With kernel command line "percpu_alloc=page" we can force percpu allocation >> to come from vmalloc area and can see kernel crash in machine_check_early: >> >> [ 1.215714] NIP [c000000000e49eb4] rcu_nmi_enter+0x24/0x110 >> [ 1.215717] LR [c0000000000461a0] machine_check_early+0xf0/0x2c0 >> [ 1.215719] --- interrupt: 200 >> [ 1.215720] [c000000fffd73180] [0000000000000000] 0x0 (unreliable) >> [ 1.215722] [c000000fffd731b0] [0000000000000000] 0x0 >> [ 1.215724] [c000000fffd73210] [c000000000008364] machine_check_early_common+0x134/0x1f8 >> >> Fix this by avoiding use of nmi_enter()/nmi_exit() in real mode if percpu >> first chunk is not embedded. >> >> CVE-2024-42126 >> Cc: stable@vger.kernel.org >> Reviewed-by: Christophe Leroy >> Tested-by: Shirisha Ganta >> Signed-off-by: Mahesh Salgaonkar >> Signed-off-by: Michael Ellerman >> Link: https://msgid.link/20240410043006.81577-1-mahesh@linux.ibm.com >> [ Conflicts in arch/powerpc/include/asm/interrupt.h >> because machine_check_early() has been refactored. ] >> Signed-off-by: Jinjie Ruan >> --- >> arch/powerpc/include/asm/percpu.h | 10 ++++++++++ >> arch/powerpc/kernel/mce.c | 14 +++++++++++--- >> arch/powerpc/kernel/setup_64.c | 2 ++ >> 3 files changed, 23 insertions(+), 3 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/percpu.h b/arch/powerpc/include/asm/percpu.h >> index 8e5b7d0b851c..634970ce13c6 100644 >> --- a/arch/powerpc/include/asm/percpu.h >> +++ b/arch/powerpc/include/asm/percpu.h >> @@ -15,6 +15,16 @@ >> #endif /* CONFIG_SMP */ >> #endif /* __powerpc64__ */ >> >> +#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) && defined(CONFIG_SMP) >> +#include >> +DECLARE_STATIC_KEY_FALSE(__percpu_first_chunk_is_paged); >> + >> +#define percpu_first_chunk_is_paged \ >> + (static_key_enabled(&__percpu_first_chunk_is_paged.key)) >> +#else >> +#define percpu_first_chunk_is_paged false >> +#endif /* CONFIG_PPC64 && CONFIG_SMP */ >> + >> #include >> >> #include >> diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c >> index 63702c0badb9..259343040e1b 100644 >> --- a/arch/powerpc/kernel/mce.c >> +++ b/arch/powerpc/kernel/mce.c >> @@ -594,8 +594,15 @@ long notrace machine_check_early(struct pt_regs *regs) >> u8 ftrace_enabled = this_cpu_get_ftrace_enabled(); >> >> this_cpu_set_ftrace_enabled(0); >> - /* Do not use nmi_enter/exit for pseries hpte guest */ >> - if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR)) >> + /* >> + * Do not use nmi_enter/exit for pseries hpte guest >> + * >> + * Likewise, do not use it in real mode if percpu first chunk is not >> + * embedded. With CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there >> + * are chances where percpu allocation can come from vmalloc area. >> + */ >> + if ((radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR)) && >> + !percpu_first_chunk_is_paged) >> nmi_enter(); >> >> hv_nmi_check_nonrecoverable(regs); >> @@ -606,7 +613,8 @@ long notrace machine_check_early(struct pt_regs *regs) >> if (ppc_md.machine_check_early) >> handled = ppc_md.machine_check_early(regs); >> >> - if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR)) >> + if ((radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR)) && >> + !percpu_first_chunk_is_paged) >> nmi_exit(); >> >> this_cpu_set_ftrace_enabled(ftrace_enabled); >> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c >> index 3f8426bccd16..899d87de0165 100644 >> --- a/arch/powerpc/kernel/setup_64.c >> +++ b/arch/powerpc/kernel/setup_64.c >> @@ -824,6 +824,7 @@ static int pcpu_cpu_distance(unsigned int from, unsigned int to) >> >> unsigned long __per_cpu_offset[NR_CPUS] __read_mostly; >> EXPORT_SYMBOL(__per_cpu_offset); >> +DEFINE_STATIC_KEY_FALSE(__percpu_first_chunk_is_paged); >> >> static void __init pcpu_populate_pte(unsigned long addr) >> { >> @@ -903,6 +904,7 @@ void __init setup_per_cpu_areas(void) >> if (rc < 0) >> panic("cannot initialize percpu area (err=%d)", rc); >> >> + static_key_enable(&__percpu_first_chunk_is_paged.key); >> delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start; >> for_each_possible_cpu(cpu) { >> __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu]; > > This looks reasonable to me, though I haven't tested it, I assume you > have done so. > > Acked-by: Michael Ellerman (powerpc) > > cheers >