CyberRota Analysis
AI-GeneratedThe vulnerability affects the Linux kernel's handling of preemption counts in the powerpc architecture, specifically within the fsl_emb_pmu_del() function. An unmatched call to put_cpu_var() can lead to a preempt_count underflow, potentially resulting in a 'scheduling while atomic' error on kernels configured with preemption enabled. Organizations using Linux on powerpc systems should prioritize addressing this issue to maintain system stability and prevent potential exploitation.
Original NVD Description
In the Linux kernel, the following vulnerability has been resolved: powerpc/perf: fix preempt count underflow in fsl_emb_pmu_del fsl_emb_pmu_del() unconditionally calls put_cpu_var(cpu_hw_events) at the 'out:' label, but only calls the matching get_cpu_var() after the 'i < 0' early-return check. When event->hw.idx is negative the function jumps to 'out:' without having taken get_cpu_var(), and the trailing put_cpu_var() then issues an unmatched preempt_enable(), underflowing preempt_count. On a CONFIG_PREEMPT=y kernel preempt_count would underflow and eventually present as a 'scheduling while atomic' BUG. Move put_cpu_var() to pair with get_cpu_var() so the percpu access is correctly bracketed and the 'out:' label only handles perf_pmu_enable.