netdev - Re: [PATCH net] ipv6: fix sparse warning on rt6i

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20170826000612.fqhjbx5oigpvqqll@kafai-mba.dhcp.thefacebook.com>
Date:   Fri, 25 Aug 2017 17:06:12 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     Wei Wang <weiwan@...gle.com>
CC:     David Miller <davem@...emloft.net>, <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH net] ipv6: fix sparse warning on rt6i_node

On Fri, Aug 25, 2017 at 03:03:10PM -0700, Wei Wang wrote:
> From: Wei Wang <weiwan@...gle.com>
>
> Commit c5cff8561d2d adds rcu grace period before freeing fib6_node. This
> generates a new sparse warning on rt->rt6i_node related code:
>   net/ipv6/route.c:1394:30: error: incompatible types in comparison
>   expression (different address spaces)
>   ./include/net/ip6_fib.h:187:14: error: incompatible types in comparison
>   expression (different address spaces)
>
> This commit adds "__rcu" tag for rt6i_node and makes sure corresponding
> rcu API is used for it.
> After this fix, sparse no longer generates the above warning.
>
> Fixes: c5cff8561d2d ("ipv6: add rcu grace period before freeing fib6_node")
> Signed-off-by: Wei Wang <weiwan@...gle.com>
> Acked-by: Eric Dumazet <edumazet@...gle.com>
Acked-by: Martin KaFai Lau <kafai@...com>

> ---
>  include/net/ip6_fib.h |  2 +-
>  net/ipv6/addrconf.c   |  2 +-
>  net/ipv6/ip6_fib.c    | 11 +++++++----
>  net/ipv6/route.c      |  3 ++-
>  4 files changed, 11 insertions(+), 7 deletions(-)
>
> diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
> index e9c59db92942..af509f801084 100644
> --- a/include/net/ip6_fib.h
> +++ b/include/net/ip6_fib.h
> @@ -105,7 +105,7 @@ struct rt6_info {
>  	 * the same cache line.
>  	 */
>  	struct fib6_table		*rt6i_table;
> -	struct fib6_node		*rt6i_node;
> +	struct fib6_node __rcu		*rt6i_node;
>
>  	struct in6_addr			rt6i_gateway;
>
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index 3c46e9513a31..936e9ab4dda5 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -5556,7 +5556,7 @@ static void __ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)
>  		 * our DAD process, so we don't need
>  		 * to do it again
>  		 */
> -		if (!(ifp->rt->rt6i_node))
> +		if (!rcu_access_pointer(ifp->rt->rt6i_node))
>  			ip6_ins_rt(ifp->rt);
>  		if (ifp->idev->cnf.forwarding)
>  			addrconf_join_anycast(ifp);
> diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
> index a5ebf86f6be8..10b4b1f8b838 100644
> --- a/net/ipv6/ip6_fib.c
> +++ b/net/ipv6/ip6_fib.c
> @@ -889,7 +889,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
>
>  		rt->dst.rt6_next = iter;
>  		*ins = rt;
> -		rt->rt6i_node = fn;
> +		rcu_assign_pointer(rt->rt6i_node, fn);
>  		atomic_inc(&rt->rt6i_ref);
>  		if (!info->skip_notify)
>  			inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
> @@ -915,7 +915,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
>  			return err;
>
>  		*ins = rt;
> -		rt->rt6i_node = fn;
> +		rcu_assign_pointer(rt->rt6i_node, fn);
>  		rt->dst.rt6_next = iter->dst.rt6_next;
>  		atomic_inc(&rt->rt6i_ref);
>  		if (!info->skip_notify)
> @@ -1480,8 +1480,9 @@ static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
>
>  int fib6_del(struct rt6_info *rt, struct nl_info *info)
>  {
> +	struct fib6_node *fn = rcu_dereference_protected(rt->rt6i_node,
> +				    lockdep_is_held(&rt->rt6i_table->tb6_lock));
>  	struct net *net = info->nl_net;
> -	struct fib6_node *fn = rt->rt6i_node;
>  	struct rt6_info **rtp;
>
>  #if RT6_DEBUG >= 2
> @@ -1670,7 +1671,9 @@ static int fib6_clean_node(struct fib6_walker *w)
>  			if (res) {
>  #if RT6_DEBUG >= 2
>  				pr_debug("%s: del failed: rt=%p@%p err=%d\n",
> -					 __func__, rt, rt->rt6i_node, res);
> +					 __func__, rt,
> +					 rcu_access_pointer(rt->rt6i_node),
> +					 res);
>  #endif
>  				continue;
>  			}
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index a9d3564caf49..33629f2a0f9d 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -1383,7 +1383,8 @@ static void rt6_do_update_pmtu(struct rt6_info *rt, u32 mtu)
>  static bool rt6_cache_allowed_for_pmtu(const struct rt6_info *rt)
>  {
>  	return !(rt->rt6i_flags & RTF_CACHE) &&
> -		(rt->rt6i_flags & RTF_PCPU || rt->rt6i_node);
> +		(rt->rt6i_flags & RTF_PCPU ||
> +		 rcu_access_pointer(rt->rt6i_node));
>  }
>
>  static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
> --
> 2.14.1.342.g6490525c54-goog
>