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Date: Mon, 20 Jul 2026 17:25:08 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Xiang Mei <xmei5@asu.edu>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>, "David S . Miller"
 <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Paolo Abeni
 <pabeni@redhat.com>, Roopa Prabhu <roopa@nvidia.com>,
 netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Petr Machata
 <petrm@nvidia.com>, Andy Roulin <aroulin@nvidia.com>, David Yang
 <mmyangfl@gmail.com>, Kees Cook <kees@kernel.org>, Weiming Shi
 <bestswngs@gmail.com>
Subject: Re: [PATCH net] vxlan: vnifilter: enforce exact length of
 GROUP/GROUP6 attributes
Message-ID: <20260720172508.6063f433@kernel.org>
In-Reply-To: <20260704222254.914567-1-xmei5@asu.edu>
References: <20260704222254.914567-1-xmei5@asu.edu>
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On Sat,  4 Jul 2026 15:22:54 -0700 Xiang Mei wrote:
> The VXLAN VNI filter entry policy declares the GROUP/GROUP6 address
> attributes as NLA_BINARY with only a maximum length, so validate_nla()
> accepts a payload shorter than the address. The GROUP consumer reads it
> with nla_get_in_addr(), an unconditional 4-byte load, so a short
> attribute over-reads up to 3 bytes of uninitialised slab data, which are
> stored into remote_ip and echoed back via RTM_GETTUNNEL, disclosing
> kernel memory.
> 
> Switch both entries to NLA_POLICY_EXACT_LEN() so the validator rejects
> any GROUP/GROUP6 that is not exactly 4 / 16 bytes; a valid address is
> always sent at full width.

The netdev patch queue has overflown, if the patch is still needed
you'll have to repost, sorry.