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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 477C0C3A5A8 for ; Wed, 4 Sep 2019 18:02:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1EC4F22CF5 for ; Wed, 4 Sep 2019 18:02:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567620147; bh=Dtb2xlJUXaI7h1jTZ4aYV373tHKBE5AMbf5Ac85jxRs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=nXZ/YsCUSZ83iGpCtceltUaMtQ2dK0G6N4Y32EVOyv+bx4KdBi4jzYm5bMQ2DNCr6 ISqcm1XQKVm+vBwGGV7mziBrwck2PRDa84tPMtzbrI463zVJ7TVyA4RlJsN3k4m3OR 9akjxJa5zcrxLSHnI0Aee4Fh//9/TNszYy7i3Zus= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388191AbfIDSC0 (ORCPT ); Wed, 4 Sep 2019 14:02:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:42248 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388738AbfIDSCX (ORCPT ); Wed, 4 Sep 2019 14:02:23 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4671622CEA; Wed, 4 Sep 2019 18:02:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567620142; bh=Dtb2xlJUXaI7h1jTZ4aYV373tHKBE5AMbf5Ac85jxRs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Nva/gb+kuXpOzuusUE1ui5RSfmjUpumLjT/VL6cMO71rGT5ffaftJWxYDJm7yUqq5 2/GyfRoh8foUnpm7mKb/jkIRNZF0ytX8JeibUFdSweQ2vsH+Z+p3+Qi74ztNKSX5m8 ajDRaBrkrBrMMH1zMWVUxg03HbeLksPk10CcMuII= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zenghui Yu , Heyi Guo , Marc Zyngier , Will Deacon , Sasha Levin Subject: [PATCH 4.9 80/83] KVM: arm/arm64: vgic: Fix potential deadlock when ap_list is long Date: Wed, 4 Sep 2019 19:54:12 +0200 Message-Id: <20190904175310.676208472@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190904175303.488266791@linuxfoundation.org> References: <20190904175303.488266791@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ Upstream commit d4a8061a7c5f7c27a2dc002ee4cb89b3e6637e44 ] If the ap_list is longer than 256 entries, merge_final() in list_sort() will call the comparison callback with the same element twice, causing a deadlock in vgic_irq_cmp(). Fix it by returning early when irqa == irqb. Cc: stable@vger.kernel.org # 4.7+ Fixes: 8e4447457965 ("KVM: arm/arm64: vgic-new: Add IRQ sorting") Signed-off-by: Zenghui Yu Signed-off-by: Heyi Guo [maz: massaged commit log and patch, added Fixes and Cc-stable] Signed-off-by: Marc Zyngier Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- virt/kvm/arm/vgic/vgic.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c index 6440b56ec90e2..1934dc8a2ce09 100644 --- a/virt/kvm/arm/vgic/vgic.c +++ b/virt/kvm/arm/vgic/vgic.c @@ -196,6 +196,13 @@ static int vgic_irq_cmp(void *priv, struct list_head *a, struct list_head *b) bool penda, pendb; int ret; + /* + * list_sort may call this function with the same element when + * the list is fairly long. + */ + if (unlikely(irqa == irqb)) + return 0; + spin_lock(&irqa->irq_lock); spin_lock_nested(&irqb->irq_lock, SINGLE_DEPTH_NESTING); -- 2.20.1