ip_tunnel: Protect ip_tunnel_net.tunnels[] with mutex.

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

struct ip_tunnel is linked to ip_tunnel_net.tunnels[] of netns.

During netns dismantle or module unload, ip_tunnel_delete_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/20260912230043.2586313-7-kuniyu@google.com
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

...

This commit is contained in:

Kuniyuki Iwashima 2026-09-12 23:00:32 +00:00 • committed by Paolo Abeni

parent 6faf19060b

commit 6724a7baf1

2 changed files with 38 additions and 5 deletions

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1

include/net/ip_tunnels.h

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42

net/ipv4/ip_tunnel.c

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