Re: [PATCH net v2] bridge: mrp: reject zero test interval to avoid OOM panic

[Ido Schimmel <idosch@nvidia.com>]

On Fri, Mar 27, 2026 at 11:30:00PM -0700, Xiang Mei wrote:
> br_mrp_start_test() and br_mrp_start_in_test() accept the user-supplied
> interval value from netlink without validation. When interval is 0,
> usecs_to_jiffies(0) yields 0, causing the delayed work
> (br_mrp_test_work_expired / br_mrp_in_test_work_expired) to reschedule
> itself with zero delay. This creates a tight loop on system_percpu_wq
> that allocates and transmits MRP test frames at maximum rate, exhausting
> all system memory and causing a kernel panic via OOM deadlock.
> 
> The same zero-interval issue applies to br_mrp_start_in_test_parse()
> for interconnect test frames.
> 
> Use NLA_POLICY_MIN(NLA_U32, 1) in the nla_policy tables for both
> IFLA_BRIDGE_MRP_START_TEST_INTERVAL and
> IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL, so zero is rejected at the
> netlink attribute parsing layer before the value ever reaches the
> workqueue scheduling code. This is consistent with how other bridge
> subsystems (br_fdb, br_mst) enforce range constraints on netlink
> attributes.
> 
> Fixes: 20f6a05ef635 ("bridge: mrp: Rework the MRP netlink interface")
> Fixes: 7ab1748e4ce6 ("bridge: mrp: Extend MRP netlink interface for configuring MRP interconnect")
> Reported-by: Weiming Shi <bestswngs@gmail.com>
> Signed-off-by: Xiang Mei <xmei5@asu.edu>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>