Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753976AbdIDSxb (ORCPT ); Mon, 4 Sep 2017 14:53:31 -0400 Received: from h2.hallyn.com ([78.46.35.8]:35864 "EHLO h2.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753932AbdIDSx3 (ORCPT ); Mon, 4 Sep 2017 14:53:29 -0400 Date: Mon, 4 Sep 2017 13:53:39 -0500 From: "Serge E. Hallyn" To: Colin King Cc: Serge Hallyn , James Morris , linux-security-module@vger.kernel.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH][capabilities-next] commoncap: move assignment of fs_ns to avoid null pointer dereference Message-ID: <20170904185339.GA11576@mail.hallyn.com> References: <20170904175005.29871-1-colin.king@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170904175005.29871-1-colin.king@canonical.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1544 Lines: 44 On Mon, Sep 04, 2017 at 06:50:05PM +0100, Colin King wrote: > 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 thanks! Acked-by: Serge Hallyn > --- > 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