CVE-2025-21657 Information

Description

In the Linux kernel the following vulnerability has been resolved:

sched_ext: Replace rq_lock() to raw_spin_rq_lock() in scx_ops_bypass()

scx_ops_bypass() iterates all CPUs to re-enqueue all the scx tasks. For each CPU it acquires a lock using rq_lock() regardless of whether a CPU is offline or the CPU is currently running a task in a higher scheduler class (e.g. deadline). The rq_lock() is supposed to be used for online CPUs and the use of rq_lock() may trigger an unnecessary warning in rq_pin_lock(). Therefore replace rq_lock() to raw_spin_rq_lock() in scx_ops_bypass().

Without this change we observe the following warning:

===== START ===== [ 6.615205] rq->balance_callback && rq->balance_callback != &balance_push_callback [ 6.615208] WARNING: CPU: 2 PID: 0 at kernel/sched/sched.h:1730 __schedule+0x1130/0x1c90 ===== END =====

Reference

https://git.kernel.org/stable/c/6268d5bc10354fc2ab8d44a0cd3b042d49a0417e https://git.kernel.org/stable/c/d9e446dd63cee7161717a6a8414ba9c6435af764