From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Florian Westphal <fw@strlen.de>
Cc: netfilter-devel@vger.kernel.org, Eric Dumazet <edumazet@google.com>
Subject: Re: [PATCH nf v2] netfilter: conntrack: dccp: copy entire header to stack buffer, not just basic one
Date: Mon, 26 Jun 2023 17:16:53 +0200 [thread overview]
Message-ID: <ZJmr5T+mdi9WUsyp@calendula> (raw)
In-Reply-To: <20230621155653.11078-1-fw@strlen.de>
On Wed, Jun 21, 2023 at 05:56:53PM +0200, Florian Westphal wrote:
> Eric Dumazet says:
> nf_conntrack_dccp_packet() has an unique:
>
> dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
>
> And nothing more is 'pulled' from the packet, depending on the content.
> dh->dccph_doff, and/or dh->dccph_x ...)
> So dccp_ack_seq() is happily reading stuff past the _dh buffer.
>
> BUG: KASAN: stack-out-of-bounds in nf_conntrack_dccp_packet+0x1134/0x11c0
> Read of size 4 at addr ffff000128f66e0c by task syz-executor.2/29371
> [..]
>
> Fix this by increasing the stack buffer to also include room for
> the extra sequence numbers and all the known dccp packet type headers,
> then pull again after the initial validation of the basic header.
>
> While at it, mark packets invalid that lack 48bit sequence bit but
> where RFC says the type MUST use them.
>
> Compile tested only.
Applied to nf.git, thanks
prev parent reply other threads:[~2023-06-26 15:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-21 15:56 [PATCH nf v2] netfilter: conntrack: dccp: copy entire header to stack buffer, not just basic one Florian Westphal
2023-06-21 20:15 ` Eric Dumazet
2023-06-26 15:16 ` Pablo Neira Ayuso [this message]
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