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=-8.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 C6D26C43381 for ; Sat, 30 Mar 2019 05:43:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 94FCB218A3 for ; Sat, 30 Mar 2019 05:43:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553924635; bh=yx1+MMpS/f+ia9+BoiS7MxiMuONqOm+udiXAsBGHQYc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=lVnS8/xCCfa/6D0bJD+TIgClm1UmyZzgwfMlpeIKwx+YzT+JDGJLkIrvp4FVOx2tb t0Qt5XS1Q8h0CcYLS/vL2f8TNphki6qI1e2K0e/B01HN76x4dNFHt3VXjKBwoZOACE B3tXEV08IV9UgtpMxaTygGq0AiC4W9rOaUmesvFg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730419AbfC3Fny (ORCPT ); Sat, 30 Mar 2019 01:43:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:38402 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726434AbfC3Fnx (ORCPT ); Sat, 30 Mar 2019 01:43:53 -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 8F3A6218A3; Sat, 30 Mar 2019 05:43:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553924633; bh=yx1+MMpS/f+ia9+BoiS7MxiMuONqOm+udiXAsBGHQYc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Ex8FwZfVtA3jrUjdWXmkmCK8fLM3JQsS8Q1a9mPmuLj253tY9NADbb6sVO4/hdVOB tzN5nDP4QEniRgnFKbcnEd1xwtNdUqGleAxPd5JUiWbcbYxlLdYdP3ap70TpCfwd2Q Ws9WIxVioIBGe/jSWNhASLVCjFImbYI5WOy4W30I= Date: Sat, 30 Mar 2019 06:43:50 +0100 From: Greg Kroah-Hartman To: Sasha Levin Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Radim =?utf-8?B?S3LEjW3DocWZ?= , kvm@vger.kernel.org, Linus Torvalds Subject: Re: [PATCH AUTOSEL 4.19 40/57] kvm: properly check debugfs dentry before using it Message-ID: <20190330054350.GB23655@kroah.com> References: <20190330012854.32212-1-sashal@kernel.org> <20190330012854.32212-40-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190330012854.32212-40-sashal@kernel.org> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 29, 2019 at 09:28:33PM -0400, Sasha Levin wrote: > 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 > Same thing here, this was a 5.0-only thing, no need for it to be backported, please drop it from all trees. thanks, greg k-h