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 7BBC6C43334 for ; Sun, 5 Jun 2022 13:53:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344216AbiFENxg (ORCPT ); Sun, 5 Jun 2022 09:53:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240021AbiFENx0 (ORCPT ); Sun, 5 Jun 2022 09:53:26 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F3B23270E; Sun, 5 Jun 2022 06:53:24 -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 E792160F9C; Sun, 5 Jun 2022 13:53:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 012DDC385A5; Sun, 5 Jun 2022 13:53:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654437203; bh=d065B4B8fmBHR6fCIbMdjWQL/kEBny/spn97THCJiJI=; h=From:To:Cc:Subject:Date:From; b=czfnQQAVUWMFM0b8cPW8zsa8xQ6Gu0FVqivM4bvy871WDOCChGWaccXQy82LJaZcv 3R9jbORCqrK8EZVy1qYYuyACyJNzMRFEG3Dtw7w/ZB3RXc2L8V+slD8isK0iPWoo2s iowPZT0f44i4zKipelr+hYA0rt0pGMIupH+JR0NgRYv14B0KSG8crAmKDY/du3AZg3 3UyJ6GZnwEsSzaC+s/XoJz7C/GuLSilUGVDTI72s2amG1igBtbSOqLtj7Rabx8RS/t SUgPVdsojVugnwbUiwLLgFdpeDP4dn/GQ438Aklm12c+OwB25hPwgkbcySBxthajOa E4ObZzAA5Em2A== 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 5.18 1/7] x86/nmi: Make register_nmi_handler() more robust Date: Sun, 5 Jun 2022 09:53:09 -0400 Message-Id: <20220605135320.61247-1-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 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 e73f7df362f5..cec0bfa3bc04 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