netdev - Re: [PATCH net-next] ipv6/addrconf: ensure addrconf_verify

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Message-ID: <8a3802ca-38a2-4baa-3e7e-8ab016eb98d5@kernel.org>
Date:   Wed, 16 Feb 2022 20:25:33 -0700
From:   David Ahern <dsahern@...nel.org>
To:     Eric Dumazet <eric.dumazet@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        syzbot <syzkaller@...glegroups.com>
Subject: Re: [PATCH net-next] ipv6/addrconf: ensure addrconf_verify_rtnl() has
 completed

On 2/16/22 11:20 AM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
> 
> Before freeing the hash table in addrconf_exit_net(),
> we need to make sure the work queue has completed,
> or risk NULL dereference or UAF.
> 
> Thus, use cancel_delayed_work_sync() to enforce this.
> We do not hold RTNL in addrconf_exit_net(), making this safe.
> 
> Fixes: 8805d13ff1b2 ("ipv6/addrconf: use one delayed work per netns")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: syzbot <syzkaller@...glegroups.com>
> ---
>  net/ipv6/addrconf.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Reviewed-by: David Ahern <dsahern@...nel.org>