From: no-reply@sashiko.virtuozzo.com
To: "Denis V. Lunev" <den@openvz.org>, khorenko@virtuozzo.com
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1] net/ip6_gre: fix a host panic adding ip6gre in a CT without ipgre
Date: Wed, 4 Nov 2026 20:31:02 +0000 [thread overview]
Message-ID: <010701a1a8420875-d0f18d8f-85ba-4933-9e33-4ac36ccea483-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261104200755.1956316-1-den@openvz.org>
> From: Denis V. Lunev <den@openvz.org>
>
> ip6gre_init_net() frees the ip6gre_net of a netns whose VE lacks
> VE_FEATURE_IPGRE, and ip6gre_newlink_common() refuses such a netns with
> -EACCES. ip6gre_newlink() and ip6erspan_newlink() reach the NULL
> ip6gre_net first, through ip6gre_tunnel_find() or collect_md_tun, so
> "ip link add type ip6gre" by root in an ordinary container panics the
> node once ip6_gre is loaded:
>
> BUG: kernel NULL pointer dereference, address: 0000000000000320
> RIP: 0010:ip6gre_tunnel_find+0x46/0xd0 [ip6_gre]
> ip6gre_newlink+0x9b/0x120 [ip6_gre]
>
> The check went into ip6gre_newlink_common(), which ran the tunnel lookup
> until upstream commit b80d0b93b991 ("net: ip6_gre: fix tunnel metadata
> device sharing.") moved the lookup into the newlink handlers. Move the
> check to the top of both handlers. They are the only callers of
> ip6gre_newlink_common() and serve as newlink for all three link types
> (ip6gre, ip6gretap and ip6erspan), and nothing else in the helper uses
> ip6gre_net.
>
> Fixes: 46c13c45f25a ("net/gre: Consider VE_FEATURE_IPGRE on new net creation")
>
> https://virtuozzo.atlassian.net/browse/VSTOR-149645
> Feature: ve: per-CT features management
> Signed-off-by: Denis V. Lunev <den@openvz.org>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261104200755.1956316-1-den@openvz.org?part=1
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prev parent reply other threads:[~2026-11-04 20:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-04 20:07 Denis V. Lunev
2026-11-04 20:31 ` no-reply [this message]
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