Linux vulnerability

What happened

In the Linux kernel, the following vulnerability has been resolved: sh: push-switch: Reorder cleanup operations to avoid use-after-free bug The original code puts flush_work() before timer_shutdown_sync() in switch_drv_remove(). Although we use flush_work() to stop the worker, it could be rescheduled in switch_timer(). As a result, a use-after-free bug can occur. The details are shown below: (cpu 0) | (cpu 1) switch_drv_remove() | flush_work() | ... | switch_timer // timer | schedule_work(&psw->work) timer_shutdown_sync() | ... | switch_work_handler // worker kfree(psw) // free | | psw->state = 0 // use This patch puts timer_shutdown_sync() before flush_work() to mitigate the bugs. As a result, the worker and timer will be stopped safely before the deallocate operations.

Affected versions

Linux: 9f5e8eee5cfe1328660c71812d87c2a67bda389f through before ff635d1f143b55fa005e9e43b16e6d8f677e90a5 (git); 9f5e8eee5cfe1328660c71812d87c2a67bda389f through before 610dbd8ac271aa36080aac50b928d700ee3fe4de (git); 9f5e8eee5cfe1328660c71812d87c2a67bda389f through before 246f80a0b17f8f582b2c0996db02998239057c65 (git); 2.6.20; 9f5e8eee5cfe through before 610dbd8ac271 (custom); 9f5e8eee5cfe through before 246f80a0b17f (custom) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.