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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_MUTT 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 7BA59C4360F for ; Wed, 3 Apr 2019 16:16:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4AE372075E for ; Wed, 3 Apr 2019 16:16:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554308174; bh=m7lFOUM4c3MvB1yjd1lFh6kMBfBqzE5Tns8BLLH1vqs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=SyGevJ4QrWci1KygHAiWOldbCXS65BMAsvhaz/0Db9SPSziITlJVXVaotF9vtnPgY 384y0dFBVu68INsvJS+/85+Iy6bfkDZStbDfHNaefpy//o7jzM8SC50SOwQ9ElZh2t HRJC8HdVZU/zP1rkn2qLvdAP5qXDXjW5C5i/vE7Y= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726155AbfDCQQI (ORCPT ); Wed, 3 Apr 2019 12:16:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:45862 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726074AbfDCQQI (ORCPT ); Wed, 3 Apr 2019 12:16:08 -0400 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 4BEC8206B7; Wed, 3 Apr 2019 16:16:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554308167; bh=m7lFOUM4c3MvB1yjd1lFh6kMBfBqzE5Tns8BLLH1vqs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nuBzjPPXVtjwxtWsz6k18Ic1+FJN26PrjM9FBGcDWazbD2xnjSJYVn8xl2Q+7g9oX gE7VuT2InZG3ub4Hu4c5c33SFiquKoWW2hQDltaoBlkukf5L82xaKmj92HBmJtnhnG oxgTdZI3pdII8uEz4+b0JqAb3AFsS+1eICwkC/Vc= Date: Wed, 3 Apr 2019 12:16:06 -0400 From: Sasha Levin To: Greg Kroah-Hartman 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: <20190403161606.GB16241@sasha-vm> References: <20190330012854.32212-1-sashal@kernel.org> <20190330012854.32212-40-sashal@kernel.org> <20190330054350.GB23655@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190330054350.GB23655@kroah.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Sat, Mar 30, 2019 at 06:43:50AM +0100, Greg Kroah-Hartman wrote: >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. Dropped, thanks! -- Thanks, Sasha