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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 E2BEEC43381 for ; Sat, 30 Mar 2019 01:38:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A1A9B217F5 for ; Sat, 30 Mar 2019 01:38:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553909927; bh=qWjm99XOLT/i8r1sif+C2VpV1a2vmTbiwYlyt1RKa+M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YK5cC/Z5tzU5p3RNDq/bk58sbkyvRIHrop2jlBSVt1IEis1uYt5gqbh6N+JSqQXOu cw4v6IuIuxduO/wZtk9JnQsUeC7VIO8SaJfAXwCFXV2QIeYr/qH1Y6sop5JeUSv7Mm ni9VbRFA0l6SQEsBEI6FtP8NvZsT6+h71SG2ICTw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731780AbfC3Biq (ORCPT ); Fri, 29 Mar 2019 21:38:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:37372 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731392AbfC3BaO (ORCPT ); Fri, 29 Mar 2019 21:30:14 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9608B218D8; Sat, 30 Mar 2019 01:30:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553909413; bh=qWjm99XOLT/i8r1sif+C2VpV1a2vmTbiwYlyt1RKa+M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lO/ZVPXTHqGKuJihWGArz9xOAgFawtfjuj0+8V7o2Hklwly+aq8iqTozeA0I42IAU SdsIOK4zso3eykEwtGB+7hGG8EA71ja3RknhCdgVL6wR8/O9o5cuxEgHPw2SnUq2Jn 56w9yIcmGghDlTYN9eMyV/0PhCpFgElDdLTO36QY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , kvm@vger.kernel.org, Linus Torvalds , Sasha Levin Subject: [PATCH AUTOSEL 4.19 40/57] kvm: properly check debugfs dentry before using it Date: Fri, 29 Mar 2019 21:28:33 -0400 Message-Id: <20190330012854.32212-40-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190330012854.32212-1-sashal@kernel.org> References: <20190330012854.32212-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Greg Kroah-Hartman [ Upstream commit 8ed0579c12b2fe56a1fac2f712f58fc26c1dc49b ] debugfs can now report an error code if something went wrong instead of just NULL. So if the return value is to be used as a "real" dentry, it needs to be checked if it is an error before dereferencing it. This is now happening because of ff9fb72bc077 ("debugfs: return error values, not NULL"). syzbot has found a way to trigger multiple debugfs files attempting to be created, which fails, and then the error code gets passed to dentry_path_raw() which obviously does not like it. Reported-by: Eric Biggers Reported-and-tested-by: syzbot+7857962b4d45e602b8ad@syzkaller.appspotmail.com Cc: "Radim Krčmář" Cc: kvm@vger.kernel.org Acked-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index c436d95fd7aa..fb74f994cb63 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3912,7 +3912,7 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm) } add_uevent_var(env, "PID=%d", kvm->userspace_pid); - if (kvm->debugfs_dentry) { + if (!IS_ERR_OR_NULL(kvm->debugfs_dentry)) { char *tmp, *p = kmalloc(PATH_MAX, GFP_KERNEL); if (p) { -- 2.19.1