From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:39716 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725936AbeJBGdL (ORCPT ); Tue, 2 Oct 2018 02:33:11 -0400 Date: Mon, 1 Oct 2018 16:52:51 -0700 From: Matthew Wilcox To: "Darrick J. Wong" Cc: viro@ZenIV.linux.org.uk, xfs , linux-fsdevel , Christoph Hellwig Subject: Re: [PATCH] vfs: check ->get_link return value Message-ID: <20181001235251.GA10425@bombadil.infradead.org> References: <20181001224500.GE5872@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181001224500.GE5872@magnolia> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Mon, Oct 01, 2018 at 03:45:00PM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong > > Teach callers of inode->i_op->get_link in the vfs code to check for a > NULL return value and return an error status instead of blindly > dereferencing the returned NULL pointer. Is that better than having the get_link method return ERR_PTR(-EUCLEAN) itself? > Signed-off-by: Darrick J. Wong > --- > fs/namei.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/fs/namei.c b/fs/namei.c > index 0cab6494978c..0744ab981fa0 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -4737,6 +4737,8 @@ int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) > if (IS_ERR(link)) > return PTR_ERR(link); > } > + if (!link) > + return -EUCLEAN; > res = readlink_copy(buffer, buflen, link); > do_delayed_call(&done); > return res; > @@ -4763,6 +4765,8 @@ const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) > res = ERR_PTR(security_inode_readlink(dentry)); > if (!res) > res = inode->i_op->get_link(dentry, inode, done); > + if (!res) > + return ERR_PTR(-EUCLEAN); > } > return res; > }