From patchwork Wed Jun 17 18:17:47 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Whitcroft X-Patchwork-Id: 485609 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 98218140218; Thu, 18 Jun 2015 04:22:17 +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 1Z5HyX-0001XZ-Sf; Wed, 17 Jun 2015 18:22:13 +0000 Received: from mail-wi0-f173.google.com ([209.85.212.173]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Z5HyS-0001XG-77 for kernel-team@lists.ubuntu.com; Wed, 17 Jun 2015 18:22:08 +0000 Received: by wiwd19 with SMTP id d19so80315wiw.0 for ; Wed, 17 Jun 2015 11:22:08 -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=yIIBNsDaFKPgzIxSfv16/YjahVI/KKbuVibIjinfEtk=; b=H6eum+6p1wMYyybRKAua7w+5ovvLpE7oEnKNFqKPJpQf7V57rUaZAtQZ4Pagh0NAj2 2+psfhzyOsRpF3dkqh4QEuwoJe1f1NLjgku6eEjEz80gQ4KIvG7mu9/rhLksOKxpIy1S yHobeP1Z4BDAU9+HxFT1zAsHyRaGPaaa1NxsHyF0VXHfi1B/VAnuTd9n/ysmq5T5tnGL RLPL9HsaBgQsjnGXuXTYk+nXxeBYVuFfUeV3GhpV/fY3KepuuNZz38O6abSRIQsWmKuq 1JWFYBWOoc7Pl4CbDnRosSEHK4EMuIlgFZOldvyvNodut3TnYG8WxPLB57FXd/ug3ICE VU/A== X-Gm-Message-State: ALoCoQmDl/mXEWHaxS7ufRsHGWGeelpH1TIKzK/7DtUQDanhdoSljg2Y4i1xUlKVMlnP0X0gfRfp X-Received: by 10.194.235.100 with SMTP id ul4mr7926478wjc.33.1434565328083; Wed, 17 Jun 2015 11:22:08 -0700 (PDT) Received: from localhost ([149.18.33.207]) by mx.google.com with ESMTPSA id xa9sm3446788wjc.43.2015.06.17.11.22.06 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Jun 2015 11:22:07 -0700 (PDT) From: Andy Whitcroft To: kernel-team@lists.ubuntu.com Subject: [precise 1/1] UBUNTU: SAUCE: ensure that upper/lower layers are valid before checking permissions Date: Wed, 17 Jun 2015 19:17:47 +0100 Message-Id: <1434565069-30669-2-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 cd55d2d..2dd897a 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -322,13 +322,16 @@ static int ovl_readdir(struct file *file, void *buf, filldir_t filler) 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, &rdd); if (res) { ovl_cache_free(rdd.list); @@ -479,13 +482,16 @@ 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, &rdd); if (err) return err;