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From: Sabrina Dubroca <sd@queasysnail.net>
To: Fernando Fernandez Mancera <fmancera@suse.de>
Cc: netdev@vger.kernel.org, bridge@lists.linux.dev,
	roopa@cumulusnetworks.com, sdf@fomichev.me, petrm@nvidia.com,
	horms@kernel.org, idosch@nvidia.com, razor@blackwall.org,
	pabeni@redhat.com, kuba@kernel.org, edumazet@google.com,
	davem@davemloft.net, andrew+netdev@lunn.ch
Subject: Re: [PATCH 2/2 net v2] net: vxlan: fix nd_tbl NULL dereference when IPv6 is disabled
Date: Mon, 2 Mar 2026 15:43:43 +0100	[thread overview]
Message-ID: <aaWiH5KBf-n1NxAR@krikkit> (raw)
In-Reply-To: <20260302140847.5941-2-fmancera@suse.de>

2026-03-02, 15:08:47 +0100, Fernando Fernandez Mancera wrote:
> When booting with the 'ipv6.disable=1' parameter, the nd_tbl is never
> initialized because inet6_init() exits before ndisc_init() is called
> which initializes it. If an IPv6 packet is injected into the interface,
> route_shortcircuit() is called and a NULL pointer dereference happens on
> neigh_lookup().

VXLAN can be built-in even when IPv6 is built as a module, and then
ipv6_mod_enabled can't be used in VXLAN:

ld: drivers/net/vxlan/vxlan_core.o: in function `route_shortcircuit':
drivers/net/vxlan/vxlan_core.c:2133:(.text+0x116e0): undefined reference to `ipv6_mod_enabled'


GENEVE has a Kconfig tweak to prevent this since 094be0927ff3
("geneve: fix build with modular IPV6"):

    depends on IPV6 || !IPV6

but VXLAN doesn't.

But then I think we don't need to use ipv6_stub at all.

-- 
Sabrina

  reply	other threads:[~2026-03-02 14:43 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-02 14:08 [PATCH 1/2 net v2] net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled Fernando Fernandez Mancera
2026-03-02 14:08 ` [PATCH 2/2 net v2] net: vxlan: " Fernando Fernandez Mancera
2026-03-02 14:43   ` Sabrina Dubroca [this message]
2026-03-02 15:13     ` Fernando Fernandez Mancera
2026-03-02 16:36       ` Ido Schimmel
2026-03-02 17:44         ` Fernando Fernandez Mancera
2026-03-02 18:04           ` Fernando Fernandez Mancera
2026-03-02 23:02             ` Sabrina Dubroca
2026-03-03 11:15               ` Fernando Fernandez Mancera

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