1 files changed, 58 insertions, 0 deletions
diff --git a/compiler-rt/lib/scudo/standalone/tests/checksum_test.cpp b/compiler-rt/lib/scudo/standalone/tests/checksum_test.cpp
new file mode 100644
index 00000000000..43bbd47a3c3
--- /dev/null
+++ b/compiler-rt/lib/scudo/standalone/tests/checksum_test.cpp
@@ -0,0 +1,58 @@
+//===-- checksum_test.cpp ---------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "checksum.h"
+
+#include "gtest/gtest.h"
+
+#include <string.h>
+
+scudo::u16 computeSoftwareChecksum(scudo::u32 Seed, scudo::uptr *Array,
+                                   scudo::uptr ArraySize) {
+  scudo::u16 Checksum = static_cast<scudo::u16>(Seed & 0xffff);
+  for (scudo::uptr I = 0; I < ArraySize; I++)
+    Checksum = scudo::computeBSDChecksum(Checksum, Array[I]);
+  return Checksum;
+}
+
+scudo::u16 computeHardwareChecksum(scudo::u32 Seed, scudo::uptr *Array,
+                                   scudo::uptr ArraySize) {
+  scudo::u32 Crc = Seed;
+  for (scudo::uptr I = 0; I < ArraySize; I++)
+    Crc = scudo::computeHardwareCRC32(Crc, Array[I]);
+  return static_cast<scudo::u16>((Crc & 0xffff) ^ (Crc >> 16));
+}
+
+typedef scudo::u16 (*ComputeChecksum)(scudo::u32, scudo::uptr *, scudo::uptr);
+
+// This verifies that flipping bits in the data being checksummed produces a
+// different checksum. We do not use random data to avoid flakyness.
+template <ComputeChecksum F> void verifyChecksumFunctionBitFlip() {
+  scudo::uptr Array[sizeof(scudo::u64) / sizeof(scudo::uptr)];
+  const scudo::uptr ArraySize = ARRAY_SIZE(Array);
+  memset(Array, 0xaa, sizeof(Array));
+  const scudo::u32 Seed = 0x41424343U;
+  const scudo::u16 Reference = F(Seed, Array, ArraySize);
+  scudo::u8 IdenticalChecksums = 0;
+  for (scudo::uptr I = 0; I < ArraySize; I++) {
+    for (scudo::uptr J = 0; J < SCUDO_WORDSIZE; J++) {
+      Array[I] ^= 1U << J;
+      if (F(Seed, Array, ArraySize) == Reference)
+        IdenticalChecksums++;
+      Array[I] ^= 1U << J;
+    }
+  }
+  // Allow for a couple of identical checksums over the whole set of flips.
+  EXPECT_LE(IdenticalChecksums, 2);
+}
+
+TEST(ScudoChecksumTest, ChecksumFunctions) {
+  verifyChecksumFunctionBitFlip<computeSoftwareChecksum>();
+  if (&scudo::computeHardwareCRC32 && scudo::hasHardwareCRC32())
+    verifyChecksumFunctionBitFlip<computeHardwareChecksum>();
+}