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=-5.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9D834C4740C for ; Mon, 9 Sep 2019 22:49:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5FFEE21479 for ; Mon, 9 Sep 2019 22:49:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="gPGWsWd3"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="OwqJ9D6J" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390141AbfIIWtV (ORCPT ); Mon, 9 Sep 2019 18:49:21 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:38586 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728945AbfIIWtV (ORCPT ); Mon, 9 Sep 2019 18:49:21 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 2AA706063A; Mon, 9 Sep 2019 22:49:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1568069360; bh=hyrKwj9FsNnKEJJvZNmfObjHJ2EoQlnM3HeyUSqoDcc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=gPGWsWd3lc9D17F205jQhOCzR+NuoRJyBrFOS19ItKyteJGkuCiDTgkuJx7LtC+Fs zXznvnBlst9XR/VFe2CEpCMDEc5zpU1lOKhnPvTYNmPLw5/pE+23aGqL/liRTQPQc/ 2LJZnK+LnVq3CLCbvlp05awQglVeZSPXE+SgOKaE= Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id C7684602BC; Mon, 9 Sep 2019 22:49:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1568069359; bh=hyrKwj9FsNnKEJJvZNmfObjHJ2EoQlnM3HeyUSqoDcc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=OwqJ9D6JwHj0MYzLLI+aQnUIsoAD386KwWnmAUCAUaV0PO0rPeu3Pcp80AtkEPd6a aeMxwNPjB7Cdp2KM+20kSHiY3AaQnO92CDny58tPFx/yEc/IkSN7x5KpN644XOC08l 6uVkXpdieIw/lvRKRszrBv1Rb1atuYrny4WduQVM= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 09 Sep 2019 15:49:19 -0700 From: rishabhb@codeaurora.org To: miklos@szeredi.hu, linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org Cc: tsoni@codeaurora.org, psodagud@codeaurora.org, jshriram@codeaurora.org Subject: Re: Bug at kernel/cred.c +443 In-Reply-To: <083b3f61efeca1d73839ac96e396748e@codeaurora.org> References: <083b3f61efeca1d73839ac96e396748e@codeaurora.org> Message-ID: <7e14f9c6fa089da67ebc28d7048c369a@codeaurora.org> X-Sender: rishabhb@codeaurora.org User-Agent: Roundcube Webmail/1.2.5 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-09-09 15:47, rishabhb@codeaurora.org wrote: > Hi Miklos > > In 4.19 kernel when we write to a file that doesn't exist we see the > following stack: > [ 377.382745] ovl_create_or_link+0xac/0x710 > [ 377.382745] ovl_create_object+0xb8/0x110 > [ 377.382745] ovl_create+0x34/0x40 > [ 377.382745] path_openat+0xd44/0x15a8 > [ 377.382745] do_filp_open+0x80/0x128 > [ 377.382745] do_sys_open+0x140/0x250 > [ 377.382745] __arm64_sys_openat+0x2c/0x38 > > If the override_cred flag = off, the ovl_override_cred and > ovl_revert_cred just returns NULL. > But there is another override_cred in between these two functions; > put_cred(override_creds(override_cred)); > put_cred(override_cred); > > This will override the credentials permanently as there is no > corresponding revert_cred associated. > So whenever we do commit_creds for this task, we see a BUG_ON at > kernel/cred.c +443. > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/cred.c#n443 > > Should this override_cred be changed to ovl_override_cred to maintain > consistency and avoid this > BUG_ON? > > > Thanks, > Rishabh Corrected line number in the subject.