Re: [PATCH net] ipv6: fix a dst leak when removing its exception

[David Miller <davem@davemloft.net>]

From: Xin Long <lucien.xin@gmail.com>
Date: Wed, 14 Nov 2018 00:48:28 +0800

> These is no need to hold dst before calling rt6_remove_exception_rt().
> The call to dst_hold_safe() in ip6_link_failure() was for ip6_del_rt(),
> which has been removed in Commit 93531c674315 ("net/ipv6: separate
> handling of FIB entries from dst based routes"). Otherwise, it will
> cause a dst leak.
> 
> This patch is to simply remove the dst_hold_safe() call before calling
> rt6_remove_exception_rt() and also do the same in ip6_del_cached_rt().
> It's safe, because the removal of the exception that holds its dst's
> refcnt is protected by rt6_exception_lock.
> 
> Fixes: 93531c674315 ("net/ipv6: separate handling of FIB entries from dst based routes")
> Fixes: 23fb93a4d3f1 ("net/ipv6: Cleanup exception and cache route handling")
> Reported-by: Li Shuang <shuali@redhat.com>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>

Applied and queued up for -stable.