netdev - Re: [PATCH net] ipv6: Fix may be used uninitialized warning in rt6

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Message-ID: <20170825075217.GW31224@secunet.com>
Date:   Fri, 25 Aug 2017 09:52:17 +0200
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     "David S. Miller" <davem@...emloft.net>
CC:     Wei Wang <weiwan@...gle.com>, Eric Dumazet <edumazet@...gle.com>,
        "Martin KaFai Lau" <kafai@...com>, <netdev@...r.kernel.org>
Subject: Re: [PATCH net] ipv6: Fix may be used uninitialized warning in
 rt6_check

On Fri, Aug 25, 2017 at 09:05:42AM +0200, Steffen Klassert wrote:
> rt_cookie might be used uninitialized, fix this by
> initializing it.
> 
> Fixes: c5cff8561d2d ("ipv6: add rcu grace period before freeing fib6_node")
> Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
> ---
>  net/ipv6/route.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index a9d3564..48c8c92 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -1289,7 +1289,7 @@ static void rt6_dst_from_metrics_check(struct rt6_info *rt)
>  
>  static struct dst_entry *rt6_check(struct rt6_info *rt, u32 cookie)
>  {
> -	u32 rt_cookie;
> +	u32 rt_cookie = 0;
>  
>  	if (!rt6_get_cookie_safe(rt, &rt_cookie) || rt_cookie != cookie)
>  		return NULL;

The compiler warning seems to be a false positive, as
rt_cookie != cookie is only checked if rt6_get_cookie_safe
returns true in which case rt_cookie is initialized.

Please disregard this patch.