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

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Message-Id: <20190322141414.496017-1-arnd@arndb.de>
Date:   Fri, 22 Mar 2019 15:14:10 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        Eric Paris <eparis@...isplace.org>
Cc:     clang-built-linux@...glegroups.com,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>, selinux@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] selinux: avoid uninitialized variable warning

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@...db.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