[Support] Properly zero initialize CPU set when querying affinity #142924
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This commit resolves a potential issue of working with uninitialized memory when querying the CPU's affinity. The man page of `sched_getaffinity` does not guarantee that the memory will be fully overwritten, so this change should ensure that issues are avoided.
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@llvm/pr-subscribers-llvm-support Author: Christian Ulmann (Dinistro) ChangesThis commit resolves a potential issue of working with uninitialized memory when querying the CPU's affinity. The man page of Full diff: https://github.com/llvm/llvm-project/pull/142924.diff 1 Files Affected:
diff --git a/llvm/lib/Support/Unix/Threading.inc b/llvm/lib/Support/Unix/Threading.inc
index 15a5b008604c3..a553230de054c 100644
--- a/llvm/lib/Support/Unix/Threading.inc
+++ b/llvm/lib/Support/Unix/Threading.inc
@@ -316,6 +316,7 @@ static int computeHostNumHardwareThreads() {
return CPU_COUNT(&mask);
#elif defined(__linux__)
cpu_set_t Set;
+ CPU_ZERO(&Set);
if (sched_getaffinity(0, sizeof(Set), &Set) == 0)
return CPU_COUNT(&Set);
#endif
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MaskRay
approved these changes
Jun 6, 2025
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This commit resolves a potential issue of working with uninitialized memory when querying the CPU's affinity. The man page of
sched_getaffinitydoes not guarantee that the memory will be fully overwritten, so this change should ensure that issues are avoided.