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 80CC4C43334 for ; Sun, 5 Jun 2022 13:57:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348917AbiFEN5u (ORCPT ); Sun, 5 Jun 2022 09:57:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351080AbiFEN4z (ORCPT ); Sun, 5 Jun 2022 09:56:55 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4196C11150; Sun, 5 Jun 2022 06:55:38 -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 694C760F9E; Sun, 5 Jun 2022 13:55:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 581BDC385A5; Sun, 5 Jun 2022 13:55:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654437336; bh=EKNSJUq7HfgUWkePjAt+SnletWZx7ex+1cUPTi1M550=; h=From:To:Cc:Subject:Date:From; b=MEye5kF++XG/ta+X17Knqe1suZ6F9jSMAkTFPAZSth/WcjDYJ0Zf6+Eov/9KsfTN+ /hAH4EAV7aaF/AeQ506pX/nhNeiiaM+f1fSr5ubiKilozA9GArDtHexrRSY4vRT9x2 GD+ZaB7jfgKiFLTp1D2CwrWYi5UhP8xLNxggqTO3HMYJOwz1aUCS/tCe66he0nc+vX 5mc4hPq0onxIoUV+HnrSkvXz+36rgz0/F+SkotImxHdZV3iVVtW37M4e0Ac31WJwFu n6gA+NByHjtx7XMgHa6Fhy8tPknbmnSQaLut8iH2tOLT9T3SxLo2/crtn3xJ32Z1Pz kP1EvxHfNnG7A== 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, peterz@infradead.org, jkosina@suse.cz Subject: [PATCH MANUALSEL 4.14 1/4] x86/nmi: Make register_nmi_handler() more robust Date: Sun, 5 Jun 2022 09:55:26 -0400 Message-Id: <20220605135533.61835-1-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: linux-kernel@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 75ded1d13d98..121bf8878506 100644 --- a/arch/x86/include/asm/nmi.h +++ b/arch/x86/include/asm/nmi.h @@ -49,6 +49,7 @@ 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 d796a7f6a74a..e8a99f11ab3f 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -159,7 +159,7 @@ 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; init_irq_work(&action->irq_work, nmi_max_handler); @@ -181,7 +181,7 @@ 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; } @@ -190,7 +190,7 @@ 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); @@ -204,12 +204,16 @@ 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