From: Florian Westphal <fw@strlen.de>
To: Mateusz Jurczyk <mjurczyk@google.com>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>,
Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
Florian Westphal <fw@strlen.de>,
"David S. Miller" <davem@davemloft.net>,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
linux-decnet-user@lists.sourceforge.net, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] decnet: dn_rtmsg: Improve input length sanitization in dnrmg_receive_user_skb
Date: Wed, 7 Jun 2017 16:18:39 +0200 [thread overview]
Message-ID: <20170607141839.GD18283@breakpoint.cc> (raw)
In-Reply-To: <20170607141429.5781-1-mjurczyk@google.com>
Mateusz Jurczyk <mjurczyk@google.com> wrote:
> Verify that the length of the socket buffer is sufficient to cover the
> nlmsghdr structure before accessing the nlh->nlmsg_len field for further
> input sanitization. If the client only supplies 1-3 bytes of data in
> sk_buff, then nlh->nlmsg_len remains partially uninitialized and
> contains leftover memory from the corresponding kernel allocation.
> Operating on such data may result in indeterminate evaluation of the
> nlmsg_len < sizeof(*nlh) expression.
>
> The bug was discovered by a runtime instrumentation designed to detect
> use of uninitialized memory in the kernel. The patch prevents this and
> other similar tools (e.g. KMSAN) from flagging this behavior in the future.
Instead of changing all the internal users wouldn't it be better
to add this check once in netlink_unicast_kernel?
next prev parent reply other threads:[~2017-06-07 14:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-07 13:14 [PATCH] decnet: dn_rtmsg: Improve input length sanitization in dnrmg_receive_user_skb Mateusz Jurczyk
2017-06-07 14:14 ` [PATCH v2] " Mateusz Jurczyk
2017-06-07 14:18 ` Florian Westphal [this message]
2017-06-07 14:41 ` Mateusz Jurczyk
2017-06-08 14:39 ` David Miller
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