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Message-ID: <6b583833-bbb1-dd59-2c83-eda747a58481@6wind.com>
Date: Fri, 26 Jul 2019 11:21:18 +0200
From: Nicolas Dichtel <nicolas.dichtel@...nd.com>
To: Jia-Ju Bai <baijiaju1990@...il.com>, davem@...emloft.net,
kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] net: ipv6: Fix a possible null-pointer dereference in
vti6_link_config()
Le 26/07/2019 à 10:03, Jia-Ju Bai a écrit :
> In vti6_link_config(), there is an if statement on line 649 to check
> whether rt is NULL:
> if (rt)
>
> When rt is NULL, it is used on line 651:
> ip6_rt_put(rt);
> dst_release(&rt->dst);
>
> Thus, a possible null-pointer dereference may occur.
>
> To fix this bug, ip6_rt_put() is called when rt is not NULL.
>
> This bug is found by a static analysis tool STCheck written by us.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
> ---
> net/ipv6/ip6_vti.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
> index 024db17386d2..572647205c52 100644
> --- a/net/ipv6/ip6_vti.c
> +++ b/net/ipv6/ip6_vti.c
> @@ -646,9 +646,10 @@ static void vti6_link_config(struct ip6_tnl *t, bool keep_mtu)
> &p->raddr, &p->laddr,
> p->link, NULL, strict);
>
> - if (rt)
> + if (rt) {
> tdev = rt->dst.dev;
> - ip6_rt_put(rt);
> + ip6_rt_put(rt);
> + }
Please, look at ip6_rt_put(), it is explicitly stated that it can be called with
rt == NULL.
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