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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 312BAC433EF for ; Sun, 5 Jun 2022 13:55:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347633AbiFENzj (ORCPT ); Sun, 5 Jun 2022 09:55:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40196 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348728AbiFENzV (ORCPT ); Sun, 5 Jun 2022 09:55:21 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3815CEE24; Sun, 5 Jun 2022 06:55:01 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C9BF860F98; Sun, 5 Jun 2022 13:54:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C7558C385A5; Sun, 5 Jun 2022 13:54:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654437291; bh=VamWnt23RJ3graitjgfrbELppOYL4yiu45gFdTZ7YF8=; h=From:To:Cc:Subject:Date:From; b=VWWvROcGKArJkabRpVeqRuAZ3rySgBZ0qQ5WzrEyXZJJbdhNH4taoRevIsBzrY1Or mcVmKLKCkzJ/rVgQX0jKzcVy9WdHtEcDm0mJLT3+F/yX0ocKnH6YfacaMU7koUjohK DhC4vmu+ev/WuYwCREkeCRCLixCE6Qj9AfsxyTcok8qad+rWcRDigTVQCtJmAl31l/ tfQpH1koI+GpR5114eK/W8RRdTOpI/DzyZCnvHnv6VANILNCIkPRDuMXMXI+LqCyee uivu5fgZbO3NbGTwmgM0S3OFouVMJMKDnLiJZxW70IUpA3OVskyY5iFVWxKUO2jB0+ MDgSeODDcyWuQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Thomas Gleixner , Sean Christopherson , Borislav Petkov , Sasha Levin , mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, jkosina@suse.cz, peterz@infradead.org Subject: [PATCH MANUALSEL 5.10 1/5] x86/nmi: Make register_nmi_handler() more robust Date: Sun, 5 Jun 2022 09:54:40 -0400 Message-Id: <20220605135447.61611-1-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Thomas Gleixner [ Upstream commit a7fed5c0431dbfa707037848830f980e0f93cfb3 ] register_nmi_handler() has no sanity check whether a handler has been registered already. Such an unintended double-add leads to list corruption and hard to diagnose problems during the next NMI handling. Init the list head in the static NMI action struct and check it for being empty in register_nmi_handler(). [ bp: Fixups. ] Reported-by: Sean Christopherson Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/lkml/20220511234332.3654455-1-seanjc@google.com Signed-off-by: Sasha Levin --- arch/x86/include/asm/nmi.h | 1 + arch/x86/kernel/nmi.c | 12 ++++++++---- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h index 9d5d949e662e..655ca59acfe7 100644 --- a/arch/x86/include/asm/nmi.h +++ b/arch/x86/include/asm/nmi.h @@ -48,6 +48,7 @@ struct nmiaction { #define register_nmi_handler(t, fn, fg, n, init...) \ ({ \ static struct nmiaction init fn##_na = { \ + .list = LIST_HEAD_INIT(fn##_na.list), \ .handler = (fn), \ .name = (n), \ .flags = (fg), \ diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index 2ef961cf4cfc..11e98d6d25e7 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -157,7 +157,7 @@ int __register_nmi_handler(unsigned int type, struct nmiaction *action) struct nmi_desc *desc = nmi_to_desc(type); unsigned long flags; - if (!action->handler) + if (WARN_ON_ONCE(!action->handler || !list_empty(&action->list))) return -EINVAL; raw_spin_lock_irqsave(&desc->lock, flags); @@ -177,7 +177,7 @@ int __register_nmi_handler(unsigned int type, struct nmiaction *action) list_add_rcu(&action->list, &desc->head); else list_add_tail_rcu(&action->list, &desc->head); - + raw_spin_unlock_irqrestore(&desc->lock, flags); return 0; } @@ -186,7 +186,7 @@ EXPORT_SYMBOL(__register_nmi_handler); void unregister_nmi_handler(unsigned int type, const char *name) { struct nmi_desc *desc = nmi_to_desc(type); - struct nmiaction *n; + struct nmiaction *n, *found = NULL; unsigned long flags; raw_spin_lock_irqsave(&desc->lock, flags); @@ -200,12 +200,16 @@ void unregister_nmi_handler(unsigned int type, const char *name) WARN(in_nmi(), "Trying to free NMI (%s) from NMI context!\n", n->name); list_del_rcu(&n->list); + found = n; break; } } raw_spin_unlock_irqrestore(&desc->lock, flags); - synchronize_rcu(); + if (found) { + synchronize_rcu(); + INIT_LIST_HEAD(&found->list); + } } EXPORT_SYMBOL_GPL(unregister_nmi_handler); -- 2.35.1