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 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 DF379C4740C for ; Mon, 9 Sep 2019 22:47:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9EB2921479 for ; Mon, 9 Sep 2019 22:47:23 +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="HL/9htVW"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="H1nCZQ0g" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730971AbfIIWrT (ORCPT ); Mon, 9 Sep 2019 18:47:19 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:37846 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728918AbfIIWrT (ORCPT ); Mon, 9 Sep 2019 18:47:19 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 3DF4360303; Mon, 9 Sep 2019 22:47:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1568069238; bh=Y/IuLwHZa6E6V0WRz+uYsMdEVK899wiCU7hIZzCVVmg=; h=Date:From:To:Cc:Subject:From; b=HL/9htVWFkKjSV91mUDuHX0XKv0jblsNAbiBfDbZbi5I4j5WX/+wjkI1Hp4jqDrkk YLatxn4yQigfEnxuzLUDmG5kZKWfEUzdPNLAJ/z1pAAk10uYYPEDAQJkW25PhLHnQt zxc3Im4lfuJd43AyQHmxwThf44JgjMex+pQtKYWQ= Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 634BE601D4; Mon, 9 Sep 2019 22:47:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1568069237; bh=Y/IuLwHZa6E6V0WRz+uYsMdEVK899wiCU7hIZzCVVmg=; h=Date:From:To:Cc:Subject:From; b=H1nCZQ0gsMeDkNuHDtvNloVBw1wimd/3P+3OX73u0ZQTRUDX+wjBOAoFSn4THkjiI XVAej3kngr+iWV26AdBoGx5SLL1klWaj78X/7d3nPeGn23VZGl8xVXbwF6Y7FWsbfO JJvPiLhrnoyqONed+VIQnrpmG1IxXiCxoRyqOQwc= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 09 Sep 2019 15:47:17 -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: Bug at kernel/cred.c +432 Message-ID: <083b3f61efeca1d73839ac96e396748e@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 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