Vulnerability CVE-2024-44958
Published: 2024-09-04

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.

 References:
https://git.kernel.org/stable/c/2a3548c7ef2e135aee40e7e5e44e7d11b893e7c4
https://git.kernel.org/stable/c/2cf7665efe451e48d27953e6b5bc627d518c902b
https://git.kernel.org/stable/c/65727331b60197b742089855ac09464c22b96f66
https://git.kernel.org/stable/c/d0c87a3c6be10a57aa3463c32c3fc6b2a47c3dab
https://git.kernel.org/stable/c/e22f910a26cc2a3ac9c66b8e935ef2a7dd881117
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