Re: [netfilter-core] [PATCH] net: netfilter: fix GCC uninitialized warning

From: Florian Westphal
Date: Fri Nov 06 2015 - 14:07:16 EST


Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote:
> On Fri, Nov 06, 2015 at 09:48:14PM +0300, Dmitry Safonov wrote:
> > 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 ânfulnl_recv_configâ:
> > net/netfilter/nfnetlink_log.c:320:14: warning: âflagsâ may be used uninitialized in this function [-Wmaybe-uninitialized]
> > inst->flags = flags;
> > ^
> > Signed-off-by: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
> > ---
> > net/netfilter/nfnetlink_log.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
> > index 06eb48fceb42e4..d65f3b987b7f13 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 flags = 0; /* GCC uninitialized */
>
> u16 uninitialized_var(flags); ?

I also see warnings in nfqueue:

net/netfilter/nfnetlink_queue.c:1083:11: warning: 'nfnl_ct' may be used uninitialized in this function [-Wmaybe-uninitialized]
net/netfilter/nfnetlink_queue.c:519:19: warning: 'nfnl_ct' may be used uninitialized in this function [-Wmaybe-uninitialized]

Both are false positives, but it would be nice if we could silence
these.
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