From: Jakub Kicinski <kuba@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
Pablo Neira Ayuso <pablo@netfilter.org>,
Jozsef Kadlecsik <kadlec@netfilter.org>,
Florian Westphal <fw@strlen.de>,
syzbot <syzkaller@googlegroups.com>,
Yajun Deng <yajun.deng@linux.dev>,
netdev@vger.kernel.org, netfilter-devel@vger.kernel.org,
coreteam@netfilter.org, Oliver Hartkopp <socketcan@hartkopp.net>,
Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH 1/2] netlink: Bounds-check nlmsg_len()
Date: Wed, 31 Aug 2022 20:18:25 -0700 [thread overview]
Message-ID: <20220831201825.378d748d@kernel.org> (raw)
In-Reply-To: <20220901030610.1121299-2-keescook@chromium.org>
On Wed, 31 Aug 2022 20:06:09 -0700 Kees Cook wrote:
> static inline int nlmsg_len(const struct nlmsghdr *nlh)
> {
> - return nlh->nlmsg_len - NLMSG_HDRLEN;
> + u32 nlmsg_contents_len;
> +
> + if (WARN_ON_ONCE(check_sub_overflow(nlh->nlmsg_len,
> + (u32)NLMSG_HDRLEN,
> + &nlmsg_contents_len)))
> + return 0;
> + if (WARN_ON_ONCE(nlmsg_contents_len > INT_MAX))
> + return INT_MAX;
> + return nlmsg_contents_len;
We check the messages on input, making sure the length is valid wrt
skb->len, and sane, ie > NLMSG_HDRLEN. See netlink_rcv_skb().
Can we not, pretty please? :(
next prev parent reply other threads:[~2022-09-01 3:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-01 3:06 [PATCH 0/2] netlink: Bounds-check struct nlmsgerr creation Kees Cook
2022-09-01 3:06 ` [PATCH 1/2] netlink: Bounds-check nlmsg_len() Kees Cook
2022-09-01 3:18 ` Jakub Kicinski [this message]
2022-09-01 6:27 ` Kees Cook
2022-09-01 19:49 ` Jakub Kicinski
2022-09-01 20:54 ` Eric Dumazet
2022-09-01 3:06 ` [PATCH 2/2] netlink: Bounds-check struct nlmsgerr creation Kees Cook
2022-09-01 3:20 ` Jakub Kicinski
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