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 34562C433EF for ; Sun, 5 Jun 2022 13:54:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240077AbiFENyV (ORCPT ); Sun, 5 Jun 2022 09:54:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239680AbiFENyU (ORCPT ); Sun, 5 Jun 2022 09:54:20 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B9783767A; Sun, 5 Jun 2022 06:54:01 -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 ams.source.kernel.org (Postfix) with ESMTPS id 4A0DCB80D9E; Sun, 5 Jun 2022 13:54:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE71CC385A5; Sun, 5 Jun 2022 13:53:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654437239; bh=DLDOxEcWpoD0bhbvCPtJURTnWAR8oyH4ncapZWZckVI=; h=From:To:Cc:Subject:Date:From; b=QvF0/+/no7A+ssv7Ewv8RlTUrUciy2VVT/EVoxtDRubxewsz5Daa9f+MVFD5gHRRO zMSGrrzjOPr45LjSL4nKQa1Doo90CLBc2Iyis0uPSi05b1b6HV2q0DuaqzwOIRwp5d nQA2AKM7mU9In6rEp8MznFt5TxEr1X6zvUwdlKju2+NjhXa/i8f5Zgw1siVDWnhvsk EonZUQdecwgGbnOZehTLGqOhy2yjsXrioYmgvTSSepiB7MBMXPVIBkiDUm2VyJ0MNy AT+MDdKIlli8AdvImKTJbuhfuFa+HEMGHsGgQSbmKDEtOZLCV76DSSWle8e3t9LLK/ UyDDLc5anUcOw== 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 5.17 1/6] x86/nmi: Make register_nmi_handler() more robust Date: Sun, 5 Jun 2022 09:53:32 -0400 Message-Id: <20220605135341.61427-1-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 1cb9c17a4cb4..5c5f1e56c404 100644 --- a/arch/x86/include/asm/nmi.h +++ b/arch/x86/include/asm/nmi.h @@ -47,6 +47,7 @@ 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 4bce802d25fb..399648421223 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