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

[Xiang Mei <xmei5@asu.edu>]

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: 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>
---
 net/bridge/br_mrp_netlink.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/bridge/br_mrp_netlink.c b/net/bridge/br_mrp_netlink.c
index ce6f63c77cc0..86f0e75d6e34 100644
--- a/net/bridge/br_mrp_netlink.c
+++ b/net/bridge/br_mrp_netlink.c
@@ -196,7 +196,7 @@ static const struct nla_policy
 br_mrp_start_test_policy[IFLA_BRIDGE_MRP_START_TEST_MAX + 1] = {
 	[IFLA_BRIDGE_MRP_START_TEST_UNSPEC]	= { .type = NLA_REJECT },
 	[IFLA_BRIDGE_MRP_START_TEST_RING_ID]	= { .type = NLA_U32 },
-	[IFLA_BRIDGE_MRP_START_TEST_INTERVAL]	= { .type = NLA_U32 },
+	[IFLA_BRIDGE_MRP_START_TEST_INTERVAL]	= NLA_POLICY_MIN(NLA_U32, 1),
 	[IFLA_BRIDGE_MRP_START_TEST_MAX_MISS]	= { .type = NLA_U32 },
 	[IFLA_BRIDGE_MRP_START_TEST_PERIOD]	= { .type = NLA_U32 },
 	[IFLA_BRIDGE_MRP_START_TEST_MONITOR]	= { .type = NLA_U32 },
@@ -316,7 +316,7 @@ static const struct nla_policy
 br_mrp_start_in_test_policy[IFLA_BRIDGE_MRP_START_IN_TEST_MAX + 1] = {
 	[IFLA_BRIDGE_MRP_START_IN_TEST_UNSPEC]	= { .type = NLA_REJECT },
 	[IFLA_BRIDGE_MRP_START_IN_TEST_IN_ID]	= { .type = NLA_U32 },
-	[IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL]	= { .type = NLA_U32 },
+	[IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL]	= NLA_POLICY_MIN(NLA_U32, 1),
 	[IFLA_BRIDGE_MRP_START_IN_TEST_MAX_MISS]	= { .type = NLA_U32 },
 	[IFLA_BRIDGE_MRP_START_IN_TEST_PERIOD]	= { .type = NLA_U32 },
 };
-- 
2.43.0