diff mbox series

selinux: avoid uninitialized variable warning

Message ID 20190322141414.496017-1-arnd@arndb.de
State Superseded
Headers show
Series selinux: avoid uninitialized variable warning | expand

Commit Message

Arnd Bergmann March 22, 2019, 2:14 p.m. UTC 
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(-)

-- 
2.20.0

Comments

Nathan Chancellor March 22, 2019, 3:17 p.m. UTC | #1 
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

>
Paul Moore March 22, 2019, 8:15 p.m. UTC | #2 
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
Arnd Bergmann March 22, 2019, 8:35 p.m. UTC | #3 
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
Paul Moore March 22, 2019, 9 p.m. UTC | #4 
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
diff mbox series

Patch

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;