From patchwork Wed Jun 17 18:17:49 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Whitcroft X-Patchwork-Id: 485611 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 420361401E7; Thu, 18 Jun 2015 04:26:37 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Z5I2i-0001xp-M4; Wed, 17 Jun 2015 18:26:32 +0000 Received: from mail-wg0-f51.google.com ([74.125.82.51]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Z5I2c-0001xG-PL for kernel-team@lists.ubuntu.com; Wed, 17 Jun 2015 18:26:26 +0000 Received: by wgv5 with SMTP id 5so44013916wgv.1 for ; Wed, 17 Jun 2015 11:26:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=yl9evqyCn/+0ofWu+UCeVlrnK0kGgd70CviQbueU5SY=; b=AZazRDuAQeWl2QQhyAL3cXR+UkDVCCeazobfx0C986hdqvMO5bSnQmgl4Bme7K2K/h 6r4+FvIjJ/5d7sTrFqZcmSvYnAATkhG4s6a1o1K3e//tstWtI+oUQ7VY0VOS6cSoZlhN yOtc3gdeymhNfhMlcyRHAdBL34VLLN9OqGmnyNKh7JlTFeZMBgDCf7AmNg7A4GTaUW6t SvwlSTa6KYiT+IyAe6PC/31EQJONoZ7xWV3MJd4DK5girTxxoDJ4TVK/uyOjo+dINi1t +nf6wCw5kACBd8uAqr8w3mpqu4M30CNcc0QjmMwdvJVnsy2+WYwK7c2s/81m9W/IcJ/O atjg== X-Gm-Message-State: ALoCoQmW0e1HiHmWxw95unlDcH9RctL/o1WWpOBKPmaPOHODt8ZmRrHoPzcxL6o7pkZ2rKmQmftm X-Received: by 10.180.81.70 with SMTP id y6mr56945654wix.14.1434565586651; Wed, 17 Jun 2015 11:26:26 -0700 (PDT) Received: from localhost ([149.18.33.207]) by mx.google.com with ESMTPSA id d3sm8976933wic.1.2015.06.17.11.26.25 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Jun 2015 11:26:25 -0700 (PDT) From: Andy Whitcroft To: kernel-team@lists.ubuntu.com Subject: [utopic 1/1] UBUNTU: SAUCE: ensure that upper/lower layers are valid before checking permissions Date: Wed, 17 Jun 2015 19:17:49 +0100 Message-Id: <1434565069-30669-4-git-send-email-apw@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1434565069-30669-1-git-send-email-apw@canonical.com> References: <1434565069-30669-1-git-send-email-apw@canonical.com> Cc: Andy Whitcroft X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com When removing a directory which was only on the lower layer and was empty on that lower layer we will attempt to confirm we are permitted to write to the upper layer when we have no upper layer. Leading to a panic. [10531.508838] BUG: unable to handle kernel NULL pointer dereference at 0000000000000030 [10531.508889] IP: [] ovl_dentry_root_may+0x30/0x60 [overlayfs] BugLink: http://bugs.launchpad.net/bugs/1465998 Signed-off-by: Andy Whitcroft --- fs/overlayfs/readdir.c | 34 ++++++++++++++++++++-------------- 1 file changed, 20 insertions(+), 14 deletions(-) diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 86bac77..6d4eb5a 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -330,13 +330,16 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx) ovl_path_lower(file->f_path.dentry, &lowerpath); ovl_path_upper(file->f_path.dentry, &upperpath); - res = ovl_dentry_root_may(file->f_path.dentry, &upperpath, MAY_READ); - if (res) - return res; - res = ovl_dentry_root_may(file->f_path.dentry, &lowerpath, MAY_READ); - if (res) - return res; - + if (upperpath.dentry) { + res = ovl_dentry_root_may(file->f_path.dentry, &upperpath, MAY_READ); + if (res) + return res; + } + if (lowerpath.dentry) { + res = ovl_dentry_root_may(file->f_path.dentry, &lowerpath, MAY_READ); + if (res) + return res; + } res = ovl_dir_read_merged(&upperpath, &lowerpath, &od->cache); if (res) { ovl_cache_free(&od->cache); @@ -481,13 +484,16 @@ static int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list) ovl_path_upper(dentry, &upperpath); ovl_path_lower(dentry, &lowerpath); - err = ovl_dentry_root_may(dentry, &upperpath, MAY_READ); - if (err) - return err; - err = ovl_dentry_root_may(dentry, &lowerpath, MAY_READ); - if (err) - return err; - + if (upperpath.dentry) { + err = ovl_dentry_root_may(dentry, &upperpath, MAY_READ); + if (err) + return err; + } + if (lowerpath.dentry) { + err = ovl_dentry_root_may(dentry, &lowerpath, MAY_READ); + if (err) + return err; + } err = ovl_dir_read_merged(&upperpath, &lowerpath, list); if (err) return err;