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,USER_AGENT_GIT autolearn=unavailable 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 13352C432C0 for ; Tue, 3 Dec 2019 22:55:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D8B8420803 for ; Tue, 3 Dec 2019 22:55:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575413749; bh=E0sg7lpUyL7wlDReSjiLpi7Lh69WU5Wh/tgGnAYTUWY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CBBTRtfy7x5D1XrTSv9LdKcEPneKuTd1sA7CU2X2eIkhhFs9/SlAkWX3qL3YC9WhL m9/kXKBwhy0HA31xfSRYsLTVYNXYGIeWEJoHD3Vc9804WWdHKzaDB7ZmrjiRfmG48y a+22EU7Sq6tcWsi/He344EfuIdMmyj5Ia+XEWkyU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730376AbfLCWzp (ORCPT ); Tue, 3 Dec 2019 17:55:45 -0500 Received: from mail.kernel.org ([198.145.29.99]:50136 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730366AbfLCWzj (ORCPT ); Tue, 3 Dec 2019 17:55:39 -0500 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 1DB692053B; Tue, 3 Dec 2019 22:55:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575413738; bh=E0sg7lpUyL7wlDReSjiLpi7Lh69WU5Wh/tgGnAYTUWY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EcvGsBeVWZAxtGbPd9NO+XarI8y0MWOw/UFbZAdY6ghP4leiDEJhwpA7F9CcBGWEi LbM3XH0stFbZ2Ko1y4VYCqrCKoaudqqSdt5fOwX0YdEXXbvOrGwzX33o9B521IbpTR 9X+p+C5KlpM9rPcOgGZb6F8ByLmYrpDE+mePB0+U= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Biggers , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , kvm@vger.kernel.org, Paolo Bonzini , Linus Torvalds , Sasha Levin , syzbot+7857962b4d45e602b8ad@syzkaller.appspotmail.com Subject: [PATCH 4.19 242/321] kvm: properly check debugfs dentry before using it Date: Tue, 3 Dec 2019 23:35:08 +0100 Message-Id: <20191203223439.731003476@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191203223427.103571230@linuxfoundation.org> References: <20191203223427.103571230@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 df3fc0f214ece..9502b1a44232c 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3990,7 +3990,7 @@ 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) { -- 2.20.1