From: Peilin Ye <yepeilin.cs@gmail.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Wensong Zhang <wensong@linux-vs.org>,
coreteam@netfilter.org, Florian Westphal <fw@strlen.de>,
LKML <linux-kernel@vger.kernel.org>,
Jozsef Kadlecsik <kadlec@netfilter.org>,
lvs-devel@vger.kernel.org, Julian Anastasov <ja@ssi.bg>,
Simon Horman <horms@verge.net.au>,
NetFilter <netfilter-devel@vger.kernel.org>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
linux-kernel-mentees@lists.linuxfoundation.org,
"David S. Miller" <davem@davemloft.net>,
Pablo Neira Ayuso <pablo@netfilter.org>
Subject: Re: [Linux-kernel-mentees] [PATCH net] ipvs: Fix uninit-value in do_ip_vs_set_ctl()
Date: Tue, 11 Aug 2020 01:09:29 -0400 [thread overview]
Message-ID: <20200811050929.GA821443@PWN> (raw)
In-Reply-To: <CAM_iQpWsQubVJ-AYaLHujHwz68+nsHBcbgbf8XPMEPD=Vu+zaA@mail.gmail.com>
On Mon, Aug 10, 2020 at 08:57:19PM -0700, Cong Wang wrote:
> On Mon, Aug 10, 2020 at 3:10 PM Peilin Ye <yepeilin.cs@gmail.com> wrote:
> >
> > do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
> > zero. Fix it.
>
> Which exact 'cmd' is it here?
>
> I _guess_ it is one of those uninitialized in set_arglen[], which is 0.
Yes, it was `IP_VS_SO_SET_NONE`, implicitly initialized to zero.
> But if that is the case, should it be initialized to
> sizeof(struct ip_vs_service_user) instead because ip_vs_copy_usvc_compat()
> is called anyway. Or, maybe we should just ban len==0 case.
I see. I think the latter would be easier, but we cannot ban all of
them, since the function does something with `IP_VS_SO_SET_FLUSH`, which
is a `len == 0` case.
Maybe we do something like this?
@@ -2432,6 +2432,8 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX)
return -EINVAL;
+ if (len == 0 && cmd != IP_VS_SO_SET_FLUSH)
+ return -EINVAL;
if (len != set_arglen[CMDID(cmd)]) {
IP_VS_DBG(1, "set_ctl: len %u != %u\n",
len, set_arglen[CMDID(cmd)]);
@@ -2547,9 +2549,6 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
break;
case IP_VS_SO_SET_DELDEST:
ret = ip_vs_del_dest(svc, &udest);
- break;
- default:
- ret = -EINVAL;
}
out_unlock:
Thank you,
Peilin Ye
> In either case, it does not look like you fix it correctly.
>
> Thanks.
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next prev parent reply other threads:[~2020-08-11 5:09 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-10 22:07 [Linux-kernel-mentees] [PATCH net] ipvs: Fix uninit-value in do_ip_vs_set_ctl() Peilin Ye
2020-08-11 3:57 ` Cong Wang
2020-08-11 5:09 ` Peilin Ye [this message]
2020-08-11 6:58 ` Julian Anastasov
2020-08-11 7:19 ` Peilin Ye
2020-08-11 7:46 ` [Linux-kernel-mentees] [PATCH net-next v2] " Peilin Ye
2020-08-11 10:29 ` Julian Anastasov
2020-08-11 12:59 ` Simon Horman
2020-08-13 1:28 ` Pablo Neira Ayuso
2020-08-28 17:21 ` Pablo Neira Ayuso
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