Executive brief
A locking issue in the Linux kernel's Mellanox network driver can cause the system to deadlock when certain traffic classification (TC) flows fail during setup. This could cause network connectivity or services relying on that driver to hang and become unresponsive.
Technical details
The vulnerability is a double-locking (AA deadlock) issue in the net/mlx5e driver's traffic classification code. When __mlx5e_add_fdb_flow() fails during flow creation, mlx5e_tc_del_flow() is called to clean up; however, it unconditionally acquires the ESW devcom lock even when the flow is marked as PEER (a duplicate flow on a peer device). Since peer flows are already created while holding the devcom lock, the unconditional re-acquisition causes a recursive lock attempt. The fix introduces a PEER flag to track peer flows and checks this flag before acquiring the lock in the deletion path. No authentication or user interaction is required; any attempt to configure certain TC flows on affected systems can trigger the deadlock.
Affected products
- Linux Linux kernel <UNKNOWN>
Timeline
- 2026-09-03: disclosed