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fix: Deadlock in Electron >= v40 #35

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Merged
timfish merged 1 commit into from
May 13, 2026
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fix: Deadlock in Electron >= v40 #35

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3 changes: 2 additions & 1 deletion bindings/cpu_profiler.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,7 @@ class MeasurementsTicker {
cpu_listeners;
v8::Isolate *isolate;
v8::HeapStatistics heap_stats;
uv_cpu_info_t cpu_stats;

public:
MeasurementsTicker(uv_loop_t *loop)
Expand Down Expand Up @@ -161,7 +162,7 @@ void MeasurementsTicker::remove_heap_listener(

// CPU tickers
void MeasurementsTicker::cpu_callback() {
uv_cpu_info_t *cpu = nullptr;
uv_cpu_info_t *cpu = &cpu_stats;

@cursor cursor Bot May 13, 2026

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Fix may be ineffective; uv_cpu_info overwrites pointer

Medium Severity

The uv_cpu_info API takes a uv_cpu_info_t** and unconditionally overwrites *cpu_infos with a pointer to newly allocated memory. This means initializing cpu to &cpu_stats vs nullptr has no effect — uv_cpu_info will still allocate, overwrite cpu, and the cpu_stats member is never read from or written to. If, however, some Electron-patched uv_cpu_info does skip allocation when *cpu_infos is non-null, then cpu would remain pointing at the single-element member cpu_stats, causing an out-of-bounds read in the loop (when count > 1) and uv_free_cpu_info would attempt to free() a class member variable — both undefined behavior.

Additional Locations (2)
Fix in Cursor Fix in Web

Reviewed by Cursor Bugbot for commit 9e90661. Configure here.

@timfish timfish May 13, 2026

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I tested this locally with Electron and it does seem to fix the issue

int count;
int err = uv_cpu_info(&cpu, &count);

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