[PATCH] D41457: [libfuzzer] Fix UB when calculating Log(0) in StackDepthStepFunction().

Max Moroz via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Dec 20 11:32:41 PST 2017

This revision was automatically updated to reflect the committed changes.
Closed by commit rCRT321211: [libfuzzer] Fix UB when calculating Log(0) in StackDepthStepFunction(). (authored by Dor1s, committed by ).

Changed prior to commit:

  rCRT Compiler Runtime



Index: lib/fuzzer/FuzzerTracePC.h
--- lib/fuzzer/FuzzerTracePC.h
+++ lib/fuzzer/FuzzerTracePC.h
@@ -276,6 +276,7 @@
   // Step function, grows similar to 8 * Log_2(A).
   auto StackDepthStepFunction = [](uint32_t A) -> uint32_t {
+    if (!A) return A;
     uint32_t Log2 = Log(A);
     if (Log2 < 3) return A;
     Log2 -= 3;

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