net: bridge: Flush multicast groups when snooping is disabled

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[ Upstream commit 68800bbf58 ]

When forwarding multicast packets, the bridge takes MDB into account when
IGMP / MLD snooping is enabled. Currently, when snooping is disabled, the
MDB is retained, even though it is not used anymore.

At the same time, during the time that snooping is disabled, the IGMP / MLD
control packets are obviously ignored, and after the snooping is reenabled,
the administrator has to assume it is out of sync. In particular, missed
join and leave messages would lead to traffic being forwarded to wrong
interfaces.

Keeping the MDB entries around thus serves no purpose, and just takes
memory. Note also that disabling per-VLAN snooping does actually flush the
relevant MDB entries.

This patch flushes non-permanent MDB entries as global snooping is
disabled.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/5e992df1bb93b88e19c0ea5819e23b669e3dde5d.1761228273.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 4df78ff026 ("bridge: mcast: Fix a possible use-after-free when removing a bridge port")
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

This commit is contained in:

Petr Machata 2025-10-23 16:45:37 +02:00 • committed by Greg Kroah-Hartman

parent 01e42aabaf

commit b081fee497

1 changed files with 9 additions and 0 deletions

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net/bridge/br_multicast.c

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