bridge: mrp: reject zero test interval to avoid OOM panic

Overview

In the Linux kernel, the following vulnerability has been resolved:

bridge: mrp: reject zero test interval to avoid OOM panic

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.

Affected

• Linux >= 20f6a05ef63594feb0c6dfbd629da0448b43124d < 610073ffb77ffd2b5eca182d2ac264de4834a175
• Linux >= 20f6a05ef63594feb0c6dfbd629da0448b43124d < ec8850be9b2b3beac1c7967d95f169dd2785979d
• Linux >= 20f6a05ef63594feb0c6dfbd629da0448b43124d < 1ec86b4b9e28170a2565cf36f0e6e2b96b55134d
• Linux >= 20f6a05ef63594feb0c6dfbd629da0448b43124d < 2120bd8546cd6a63c558d135773aa8f41c8259fc
• Linux >= 20f6a05ef63594feb0c6dfbd629da0448b43124d < 630a15a31c2034b5b697f4aabc769b9d80d82446
• Linux >= 20f6a05ef63594feb0c6dfbd629da0448b43124d < e8ec80430bfa520e7352155d6ac632e527cba7aa
• Linux >= 20f6a05ef63594feb0c6dfbd629da0448b43124d < c9bc352f716d1bebfe43354bce539ec2d0223b30
• Linux >= 20f6a05ef63594feb0c6dfbd629da0448b43124d < fa6e24963342de4370e3a3c9af41e38277b74cf3
• Linux 5.8

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.