ip6_gre: Protect ip6gre_net.tunnels[][] with mutex.

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struct ip6_tnl.net is the netns where encapsulated packets
flow into.

struct ip6_tnl is linked to ip6gre_net.tunnels[][] of netns.

During netns dismantle or module unload, ip6gre_exit_rtnl_net()
iterates the list and queues devices for destruction regardless
of the devices' netns.

Thus, once RTNL is removed, the list can be modified concurrently
from different netns due to device removal.

Let's protect it with per-netns mutex.

Note that dev_siocdevprivate() calls netdev_lock_ops() but
it must be NOP for tunnel devices to avoid AB-BA deadlock.
DEBUG_NET_WARN_ON_ONCE() is added to annotate the locking
explicitly.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260916230353.367014-6-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

...

This commit is contained in:

Kuniyuki Iwashima 2026-09-16 23:02:24 +00:00 • committed by Jakub Kicinski

parent b7c0d393e1

commit cce829e2aa

1 changed files with 65 additions and 13 deletions

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net/ipv6/ip6_gre.c

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