linux-kernel - [PATCH] net: netfilter: fix false positive GCC warnings

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Date:	Fri,  6 Nov 2015 22:35:44 +0300
From:	Dmitry Safonov <0x7f454c46@...il.com>
To:	pablo@...filter.org, kaber@...sh.net, kadlec@...ckhole.kfki.hu,
	davem@...emloft.net
Cc:	netfilter-devel@...r.kernel.org, coreteam@...filter.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Dmitry Safonov <0x7f454c46@...il.com>
Subject: [PATCH] net: netfilter: fix false positive GCC warnings

With x86_64_defconfig:
GCC thinks that in nfulnl_recv_config flags parameter is not inited but
it was under the same condition (nfula[NFULA_CFG_FLAGS] == true).
Suppress this warning:
        net/netfilter/nfnetlink_log.c: In function ‘nfulnl_recv_config’:
        net/netfilter/nfnetlink_log.c:320:14: warning: ‘flags’ may be used uninitialized in this function [-Wmaybe-uninitialized]
        inst->flags = flags;
                    ^
GCC thinks that nfnl_ct wasn't inited, but it is used only under
	if (ct && diff)
where ct is not NULL only when nfnl_ct is inited.

Reported-by: Florian Westphal <fw@...len.de>
Signed-off-by: Dmitry Safonov <0x7f454c46@...il.com>
---
 net/netfilter/nfnetlink_log.c   | 2 +-
 net/netfilter/nfnetlink_queue.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index 06eb48fceb42e4..23f16b99e6388a 100644
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -825,7 +825,7 @@ nfulnl_recv_config(struct sock *ctnl, struct sk_buff *skb,
 	struct net *net = sock_net(ctnl);
 	struct nfnl_log_net *log = nfnl_log_pernet(net);
 	int ret = 0;
-	u16 flags;
+	u16 uninitialized_var(flags);
 
 	if (nfula[NFULA_CFG_CMD]) {
 		u_int8_t pf = nfmsg->nfgen_family;
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index 7d81d280cb4ff3..66b006112921ca 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -313,7 +313,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
 	struct net_device *outdev;
 	struct nf_conn *ct = NULL;
 	enum ip_conntrack_info uninitialized_var(ctinfo);
-	struct nfnl_ct_hook *nfnl_ct;
+	struct nfnl_ct_hook *uninitialized_var(nfnl_ct);
 	bool csum_verify;
 	char *secdata = NULL;
 	u32 seclen = 0;
@@ -1041,7 +1041,7 @@ nfqnl_recv_verdict(struct sock *ctnl, struct sk_buff *skb,
 	unsigned int verdict;
 	struct nf_queue_entry *entry;
 	enum ip_conntrack_info uninitialized_var(ctinfo);
-	struct nfnl_ct_hook *nfnl_ct;
+	struct nfnl_ct_hook *uninitialized_var(nfnl_ct);
 	struct nf_conn *ct = NULL;
 
 	struct net *net = sock_net(ctnl);
-- 
2.6.2

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