From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joonwon Kang Date: Thu, 01 Aug 2019 13:41:49 +0000 Subject: Re: [PATCH 2/2] randstruct: remove dead code in is_pure_ops_struct() Message-Id: <20190801134149.GA2149@host> List-Id: References: <281a65cc361512e3dc6c5deffa324f800eb907be.1564595346.git.kjw1627@gmail.com> <201907311259.D485EED2B7@keescook> In-Reply-To: <201907311259.D485EED2B7@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Kees Cook Cc: re.emese@gmail.com, kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, jinb.park7@gmail.com On Wed, Jul 31, 2019 at 12:59:30PM -0700, Kees Cook wrote: > On Thu, Aug 01, 2019 at 03:01:49AM +0900, Joonwon Kang wrote: > > Recursive declaration for struct which has member of the same struct > > type, for example, > > > > struct foo { > > struct foo f; > > ... > > }; > > > > is not allowed. So, it is unnecessary to check if a struct has this > > kind of member. > > Is that the only case where this loop could happen? Seems also safe to > just leave it as-is... > > -Kees I think it is pretty obvious that it is the only case. I compiled kernel with allyesconfig and the condition never hit even once. However, it will also be no problem to just leave it as-is as you mentioned. > > > > > Signed-off-by: Joonwon Kang > > --- > > scripts/gcc-plugins/randomize_layout_plugin.c | 3 --- > > 1 file changed, 3 deletions(-) > > > > diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c > > index bd29e4e7a524..e14efe23e645 100644 > > --- a/scripts/gcc-plugins/randomize_layout_plugin.c > > +++ b/scripts/gcc-plugins/randomize_layout_plugin.c > > @@ -440,9 +440,6 @@ static int is_pure_ops_struct(const_tree node) > > const_tree fieldtype = get_field_type(field); > > enum tree_code code = TREE_CODE(fieldtype); > > > > - if (node = fieldtype) > > - continue; > > - > > if (code = RECORD_TYPE || code = UNION_TYPE) { > > if (!is_pure_ops_struct(fieldtype)) > > return 0; > > -- > > 2.17.1 > > > > -- > Kees Cook