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* [PATCH] selinux: avoid uninitialized variable warning
@ 2019-03-22 14:14 Arnd Bergmann
  2019-03-22 15:17 ` Nathan Chancellor
  2019-03-22 20:15 ` Paul Moore
  0 siblings, 2 replies; 5+ messages in thread
From: Arnd Bergmann @ 2019-03-22 14:14 UTC (permalink / raw)
  To: Paul Moore, Stephen Smalley, Eric Paris
  Cc: clang-built-linux, Nick Desaulniers, Nathan Chancellor,
	Arnd Bergmann, selinux, linux-kernel

clang correctly points out a code path that would lead
to an uninitialized variable use:

security/selinux/netlabel.c:310:6: error: variable 'addr' is used uninitialized whenever 'if' condition is false
      [-Werror,-Wsometimes-uninitialized]
        if (ip_hdr(skb)->version == 4) {
            ^~~~~~~~~~~~~~~~~~~~~~~~~
security/selinux/netlabel.c:322:40: note: uninitialized use occurs here
        rc = netlbl_conn_setattr(ep->base.sk, addr, &secattr);
                                              ^~~~
security/selinux/netlabel.c:310:2: note: remove the 'if' if its condition is always true
        if (ip_hdr(skb)->version == 4) {
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
security/selinux/netlabel.c:291:23: note: initialize the variable 'addr' to silence this warning
        struct sockaddr *addr;
                             ^
                              = NULL
1 error generated.

This is probably harmless since we should not see ipv6 packets
of CONFIG_IPV6 is disabled, but it's better to rearrange the code
so this cannot happen.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 security/selinux/netlabel.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

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
 	}
 
-	rc = netlbl_conn_setattr(ep->base.sk, addr, &secattr);
 	if (rc == 0)
 		sksec->nlbl_state = NLBL_LABELED;
 
-- 
2.20.0


^ permalink raw reply related	[flat|nested] 5+ messages in thread
* Re: [PATCH] selinux: avoid uninitialized variable warning
  2019-03-22 14:14 [PATCH] selinux: avoid uninitialized variable warning Arnd Bergmann
@ 2019-03-22 15:17 ` Nathan Chancellor
  2019-03-22 20:15 ` Paul Moore
  1 sibling, 0 replies; 5+ messages in thread
From: Nathan Chancellor @ 2019-03-22 15:17 UTC (permalink / raw)
  To: Arnd Bergmann
  Cc: Paul Moore, Stephen Smalley, Eric Paris, clang-built-linux,
	Nick Desaulniers, selinux, linux-kernel

On Fri, Mar 22, 2019 at 03:14:10PM +0100, Arnd Bergmann wrote:
> clang correctly points out a code path that would lead
> to an uninitialized variable use:
> 
> security/selinux/netlabel.c:310:6: error: variable 'addr' is used uninitialized whenever 'if' condition is false
>       [-Werror,-Wsometimes-uninitialized]
>         if (ip_hdr(skb)->version == 4) {
>             ^~~~~~~~~~~~~~~~~~~~~~~~~
> security/selinux/netlabel.c:322:40: note: uninitialized use occurs here
>         rc = netlbl_conn_setattr(ep->base.sk, addr, &secattr);
>                                               ^~~~
> security/selinux/netlabel.c:310:2: note: remove the 'if' if its condition is always true
>         if (ip_hdr(skb)->version == 4) {
>         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> security/selinux/netlabel.c:291:23: note: initialize the variable 'addr' to silence this warning
>         struct sockaddr *addr;
>                              ^
>                               = NULL
> 1 error generated.
> 
> This is probably harmless since we should not see ipv6 packets
> of CONFIG_IPV6 is disabled, but it's better to rearrange the code
> so this cannot happen.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>

> ---
>  security/selinux/netlabel.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> 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
>  	}
>  
> -	rc = netlbl_conn_setattr(ep->base.sk, addr, &secattr);
>  	if (rc == 0)
>  		sksec->nlbl_state = NLBL_LABELED;
>  
> -- 
> 2.20.0
> 

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [PATCH] selinux: avoid uninitialized variable warning
  2019-03-22 14:14 [PATCH] selinux: avoid uninitialized variable warning Arnd Bergmann
  2019-03-22 15:17 ` Nathan Chancellor
@ 2019-03-22 20:15 ` Paul Moore
  2019-03-22 20:35   ` Arnd Bergmann
  1 sibling, 1 reply; 5+ messages in thread
From: Paul Moore @ 2019-03-22 20:15 UTC (permalink / raw)
  To: Arnd Bergmann
  Cc: Stephen Smalley, Eric Paris, clang-built-linux, Nick Desaulniers,
	Nathan Chancellor, selinux, linux-kernel

On Fri, Mar 22, 2019 at 10:14 AM Arnd Bergmann <arnd@arndb.de> wrote:
> clang correctly points out a code path that would lead
> to an uninitialized variable use:
>
> security/selinux/netlabel.c:310:6: error: variable 'addr' is used uninitialized whenever 'if' condition is false
>       [-Werror,-Wsometimes-uninitialized]
>         if (ip_hdr(skb)->version == 4) {
>             ^~~~~~~~~~~~~~~~~~~~~~~~~
> security/selinux/netlabel.c:322:40: note: uninitialized use occurs here
>         rc = netlbl_conn_setattr(ep->base.sk, addr, &secattr);
>                                               ^~~~
> security/selinux/netlabel.c:310:2: note: remove the 'if' if its condition is always true
>         if (ip_hdr(skb)->version == 4) {
>         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> security/selinux/netlabel.c:291:23: note: initialize the variable 'addr' to silence this warning
>         struct sockaddr *addr;
>                              ^
>                               = NULL
> 1 error generated.
>
> This is probably harmless since we should not see ipv6 packets
> of CONFIG_IPV6 is disabled, but it's better to rearrange the code
> so this cannot happen.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  security/selinux/netlabel.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)

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?

>         }
>
> -       rc = netlbl_conn_setattr(ep->base.sk, addr, &secattr);
>         if (rc == 0)
>                 sksec->nlbl_state = NLBL_LABELED;
>
> --
> 2.20.0
>

-- 
paul moore
www.paul-moore.com

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [PATCH] selinux: avoid uninitialized variable warning
  2019-03-22 20:15 ` Paul Moore
@ 2019-03-22 20:35   ` Arnd Bergmann
  2019-03-22 21:00     ` Paul Moore
  0 siblings, 1 reply; 5+ messages in thread
From: Arnd Bergmann @ 2019-03-22 20:35 UTC (permalink / raw)
  To: Paul Moore
  Cc: Stephen Smalley, Eric Paris, clang-built-linux, Nick Desaulniers,
	Nathan Chancellor, selinux, Linux Kernel Mailing List

On Fri, Mar 22, 2019 at 9:15 PM Paul Moore <paul@paul-moore.com> wrote:
> On Fri, Mar 22, 2019 at 10:14 AM Arnd Bergmann <arnd@arndb.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;
        }

  Arnd

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [PATCH] selinux: avoid uninitialized variable warning
  2019-03-22 20:35   ` Arnd Bergmann
@ 2019-03-22 21:00     ` Paul Moore
  0 siblings, 0 replies; 5+ messages in thread
From: Paul Moore @ 2019-03-22 21:00 UTC (permalink / raw)
  To: Arnd Bergmann
  Cc: Stephen Smalley, Eric Paris, clang-built-linux, Nick Desaulniers,
	Nathan Chancellor, selinux, Linux Kernel Mailing List

On Fri, Mar 22, 2019 at 4:35 PM Arnd Bergmann <arnd@arndb.de> wrote:
> On Fri, Mar 22, 2019 at 9:15 PM Paul Moore <paul@paul-moore.com> wrote:
> > On Fri, Mar 22, 2019 at 10:14 AM Arnd Bergmann <arnd@arndb.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

^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-03-22 21:00 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-03-22 14:14 [PATCH] selinux: avoid uninitialized variable warning Arnd Bergmann
2019-03-22 15:17 ` Nathan Chancellor
2019-03-22 20:15 ` Paul Moore
2019-03-22 20:35   ` Arnd Bergmann
2019-03-22 21:00     ` Paul Moore

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