linux-kernel - Re: [PATCH] selinux: avoid uninitialized variable warning

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Date:   Fri, 22 Mar 2019 17:00:13 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Stephen Smalley <sds@...ho.nsa.gov>,
        Eric Paris <eparis@...isplace.org>,
        clang-built-linux@...glegroups.com,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        selinux@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] selinux: avoid uninitialized variable warning

On Fri, Mar 22, 2019 at 4:35 PM Arnd Bergmann <arnd@...db.de> wrote:
> On Fri, Mar 22, 2019 at 9:15 PM Paul Moore <paul@...l-moore.com> wrote:
> > On Fri, Mar 22, 2019 at 10:14 AM Arnd Bergmann <arnd@...db.de> wrote:
>
> > Hi Arnd,
> >
> > Thanks for pointing this out and providing a fix.  I think you're
> > right in that the should be pretty harmless, but I also agree that we
> > should fix it; some thoughts on the patch below ...
> >
> > > diff --git a/security/selinux/netlabel.c b/security/selinux/netlabel.c
> > > index 186e727b737b..d0e549d4f486 100644
> > > --- a/security/selinux/netlabel.c
> > > +++ b/security/selinux/netlabel.c
> > > @@ -288,7 +288,6 @@ int selinux_netlbl_sctp_assoc_request(struct sctp_endpoint *ep,
> > >         int rc;
> > >         struct netlbl_lsm_secattr secattr;
> > >         struct sk_security_struct *sksec = ep->base.sk->sk_security;
> > > -       struct sockaddr *addr;
> > >         struct sockaddr_in addr4;
> > >  #if IS_ENABLED(CONFIG_IPV6)
> > >         struct sockaddr_in6 addr6;
> > > @@ -310,16 +309,15 @@ int selinux_netlbl_sctp_assoc_request(struct sctp_endpoint *ep,
> > >         if (ip_hdr(skb)->version == 4) {
> > >                 addr4.sin_family = AF_INET;
> > >                 addr4.sin_addr.s_addr = ip_hdr(skb)->saddr;
> > > -               addr = (struct sockaddr *)&addr4;
> > > +               rc = netlbl_conn_setattr(ep->base.sk, (void*)&addr4, &secattr);
> > >  #if IS_ENABLED(CONFIG_IPV6)
> > >         } else {
> > >                 addr6.sin6_family = AF_INET6;
> > >                 addr6.sin6_addr = ipv6_hdr(skb)->saddr;
> > > -               addr = (struct sockaddr *)&addr6;
> > > +               rc = netlbl_conn_setattr(ep->base.sk, (void*)&addr6, &secattr);
> > >  #endif
> >
> > While we are hardening the code a bit, I'm thinking we should probably
> > refactor this if-else a bit, some pseudo code for example:
> >
> >     if (ip_hdr == 4) {
> >       rc = netlbl_conn_setattr();
> >   #if CONFIG_IPV6
> >     } else if (ip_hdr == 6) {
> >       rc = netlbl_conn_setattr();
> >   #endif
> >     } else {
> >       rc = -EAFNOSUPPORT;
> >     }
> >
> > Thoughts?
> >
>
> Seems fine. We could go a step further and use IS_ENABLED()
> as C code here to get rid of the two #ifdef checks as well, like
>
>         if (ip_hdr(skb)->version == 4 ) {
>                 addr4.sin_family = AF_INET;
>                 addr4.sin_addr.s_addr = ip_hdr(skb)->saddr;
>                 rc = netlbl_conn_setattr(ep->base.sk, &addr4, &secattr);
>         } else if (IS_ENABLED(CONFIG_IPV6) && ip_hdr(skb)->version == 6) {
>                 addr6.sin6_family = AF_INET6;
>                 addr6.sin6_addr = ipv6_hdr(skb)->saddr;
>                 rc = netlbl_conn_setattr(ep->base.sk, &addr6, &secattr);
>         } else {
>                rc = -EAFNOSUPPORT;
>         }

Looks good to me.  Can you send a revised patch?

-- 
paul moore
www.paul-moore.com