CVE-2024-44958: sched/smt: Fix unbalance sched_smt_present dec/inc

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-09-04 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: sched/smt: Fix unbalance sched_smt_present dec/inc I got the following warn report while doing stress test: jump label: negative count! WARNING: CPU: 3 PID: 38 at kernel/jump_label.c:263 static_key_slow_try_dec+0x9d/0xb0 Call Trace: <TASK> __static_key_slow_dec_cpuslocked+0x16/0x70 sched_cpu_deactivate+0x26e/0x2a0 cpuhp_invoke_callback+0x3ad/0x10d0 cpuhp_thread_fun+0x3f5/0x680 smpboot_thread_fn+0x56d/0x8d0 kthread+0x309/0x400 ret_from_fork+0x41/0x70 ret_from_fork_asm+0x1b/0x30 </TASK> Because when cpuset_cpu_inactive() fails in sched_cpu_deactivate(), the cpu offline failed, but sched_smt_present is decremented before calling sched_cpu_deactivate(), it leads to unbalanced dec/inc, so fix it by incrementing sched_smt_present in the error path.

Affected products

Linux kernel: from 4.14.86 before 4.15; from 4.19.7 before 4.20; from 4.20 before 5.15.165; from 5.16 before 6.1.105; from 6.2 before 6.6.46; from 6.7 before 6.10.5 — fixed in 4.15, 4.20, 5.15.165, 6.1.105, 6.10.5, 6.6.46

How to fix

Upgrade to a fixed version: Linux kernel 4.15, 4.20, 5.15.165, 6.1.105. Check the vendor advisory for mitigations.

References

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