From nobody Fri Dec 19 19:08:40 2025 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7CDBE6A01E for ; Mon, 5 Aug 2024 11:48:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.255 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722858497; cv=none; b=BC9Z1Mqeyyzp9RcAUDlbnv5dA7qg3VeKmCUEF754omu/+ni0rA7QOS/JwF7VO09wWaImsfafBPhx152ulq2Slq0OxV2vLk2jpRSo35d1kt8mTLT+SAFgoplMS9F0TGiPEUOgk02PBJhhdAgso8d0rJEEwBcTJE2HZR8Xeq98CaM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722858497; c=relaxed/simple; bh=yHcOcJpTJCXcm2Yyz5sSIefo0DzbP+DGGdlPpfbgeEE=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=nCSr6uFgC51S9oo9Q/xHy1MfOVhc4bj/jniaSOTG4DhcXBTOAXlwQ3XruWJpMW4iMK9i6+wAxWkx7j4fQfApsUXvm9RDlLeDFrRoeLdYK1er1colw4FnjCHVo6I702NPtMeN1nQOakifsSfBkslojz+LMo51sTY2CHR0sYGlho4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.255 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.174]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4Wcvnb0b1wz1L9sm; Mon, 5 Aug 2024 19:47:47 +0800 (CST) Received: from kwepemi100008.china.huawei.com (unknown [7.221.188.57]) by mail.maildlp.com (Postfix) with ESMTPS id F2133140109; Mon, 5 Aug 2024 19:48:04 +0800 (CST) Received: from huawei.com (10.67.174.55) 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; Mon, 5 Aug 2024 19:48:04 +0800 From: Jinjie Ruan To: , , , , , , , , , , CC: Subject: [PATCH v5.10] powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt. Date: Mon, 5 Aug 2024 11:45:44 +0000 Message-ID: <20240805114544.1552341-1-ruanjinjie@huawei.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemi100008.china.huawei.com (7.221.188.57) Content-Type: text/plain; charset="utf-8" From: Mahesh Salgaonkar 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=3Dpage" we can force percpu allocati= on 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_co= mmon+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 Acked-by: Michael Ellerman (powerpc) --- 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/p= ercpu.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__ */ =20 +#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 =20 #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 =3D this_cpu_get_ftrace_enabled(); =20 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(); =20 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 =3D ppc_md.machine_check_early(regs); =20 - 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(); =20 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, unsigne= d int to) =20 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly; EXPORT_SYMBOL(__per_cpu_offset); +DEFINE_STATIC_KEY_FALSE(__percpu_first_chunk_is_paged); =20 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=3D%d)", rc); =20 + static_key_enable(&__percpu_first_chunk_is_paged.key); delta =3D (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start; for_each_possible_cpu(cpu) { __per_cpu_offset[cpu] =3D delta + pcpu_unit_offsets[cpu]; --=20 2.34.1