Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753971AbdIDRuJ (ORCPT ); Mon, 4 Sep 2017 13:50:09 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:59978 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753912AbdIDRuH (ORCPT ); Mon, 4 Sep 2017 13:50:07 -0400 From: Colin King To: Serge Hallyn , James Morris , linux-security-module@vger.kernel.org Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH][capabilities-next] commoncap: move assignment of fs_ns to avoid null pointer dereference Date: Mon, 4 Sep 2017 18:50:05 +0100 Message-Id: <20170904175005.29871-1-colin.king@canonical.com> X-Mailer: git-send-email 2.14.1 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1355 Lines: 38 From: Colin Ian King The pointer fs_ns is assigned from inode->i_ib->s_user_ns before a null pointer check on inode, hence if inode is actually null we will get a null pointer dereference on this assignment. Fix this by only dereferencing inode after the null pointer check on inode. Detected by CoverityScan CID#1455328 ("Dereference before null check") Fixes: 8db6c34f1dbc ("Introduce v3 namespaced file capabilities") Signed-off-by: Colin Ian King --- security/commoncap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/security/commoncap.c b/security/commoncap.c index c25e0d27537f..fc46f5b85251 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -585,13 +585,14 @@ int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data struct vfs_ns_cap_data data, *nscaps = &data; struct vfs_cap_data *caps = (struct vfs_cap_data *) &data; kuid_t rootkuid; - struct user_namespace *fs_ns = inode->i_sb->s_user_ns; + struct user_namespace *fs_ns; memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); if (!inode) return -ENODATA; + fs_ns = inode->i_sb->s_user_ns; size = __vfs_getxattr((struct dentry *)dentry, inode, XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ); if (size == -ENODATA || size == -EOPNOTSUPP) -- 2.14.1