Handle empty crash signatures and descriptions in crash deduplication.

centipede/crash_deduplication.cc

@@ -15,6 +15,7 @@
 #include "./centipede/crash_deduplication.h"
 
 #include <cstddef>
+#include <cstdlib>
 #include <filesystem>  // NOLINT
 #include <string>
 #include <string_view>
@@ -53,6 +54,8 @@ std::string GetInputFileName(std::string_view bug_id,
 
 absl::flat_hash_map<std::string, CrashDetails> GetCrashesFromWorkdir(
     const WorkDir& workdir, size_t total_shards) {
+  const bool fail_on_empty_crash_metadata =
+      std::getenv("FUZZTEST_FAIL_ON_EMPTY_CRASH_METADATA") != nullptr;
   absl::flat_hash_map<std::string, CrashDetails> crashes;
   for (size_t shard_idx = 0; shard_idx < total_shards; ++shard_idx) {
     std::vector<std::string> crashing_input_paths =
@@ -79,16 +82,38 @@ absl::flat_hash_map<std::string, CrashDetails> GetCrashesFromWorkdir(
             << " due to failure to read the crash signature: " << status;
         continue;
       }
+      if (crash_signature.empty()) {
+        FUZZTEST_LOG_IF(FATAL, fail_on_empty_crash_metadata)
+            << "Empty crash signature for " << crashing_input_file_name;
+        FUZZTEST_LOG(ERROR)
+            << "Ignoring crashing input " << crashing_input_file_name
+            << " due to empty crash signature. This is an internal error; "
+               "please report it to the FuzzTest team!";
+        continue;
+      }
       if (crashes.contains(crash_signature)) continue;
 
       const std::string crash_description_path =
           crash_metadata_dir / absl::StrCat(crashing_input_file_name, ".desc");
       std::string crash_description;
       const absl::Status description_status =
           RemoteFileGetContents(crash_description_path, crash_description);
-      FUZZTEST_LOG_IF(WARNING, !description_status.ok())
-          << "Failed to read crash description for " << crashing_input_file_name
-          << ".Status: " << description_status;
+      if (!description_status.ok()) {
+        FUZZTEST_LOG(WARNING)
+            << "Ignoring crashing input " << crashing_input_file_name
+            << " due to failure to read the crash description: "
+            << description_status;
+        continue;
+      }
+      if (crash_description.empty()) {
+        FUZZTEST_LOG_IF(FATAL, fail_on_empty_crash_metadata)
+            << "Empty crash description for " << crashing_input_file_name;
+        FUZZTEST_LOG(ERROR)
+            << "Ignoring crashing input " << crashing_input_file_name
+            << " due to empty crash description. This is an internal error; "
+               "please report it to the FuzzTest team!";
+        continue;
+      }
       crashes.insert(
           {std::move(crash_signature),
            // Centipede uses the input signature (i.e., the hash of the input)

centipede/crash_deduplication_test.cc

@@ -91,6 +91,16 @@ TEST(GetCrashesFromWorkdirTest, ReturnsOneCrashPerCrashSignature) {
   // `isig4` lacks `.sig` and `.desc` files and should be ignored.
   SetContentsAndGetPath(crashes1, "isig4", "input4");
 
+  // `isig5` has empty crash signature and should be ignored.
+  auto input5_path = SetContentsAndGetPath(crashes1, "isig5", "input5");
+  SetContentsAndGetPath(crash_metadata1, "isig5.sig", "");
+  SetContentsAndGetPath(crash_metadata1, "isig5.desc", "desc5");
+
+  // `isig6` has empty crash description and should be ignored.
+  auto input6_path = SetContentsAndGetPath(crashes1, "isig6", "input6");
+  SetContentsAndGetPath(crash_metadata1, "isig6.sig", "csig6");
+  SetContentsAndGetPath(crash_metadata1, "isig6.desc", "");
+
   const auto crashes = GetCrashesFromWorkdir(workdir, /*total_shards=*/2);
   EXPECT_THAT(
       crashes,
@@ -100,6 +110,52 @@ TEST(GetCrashesFromWorkdirTest, ReturnsOneCrashPerCrashSignature) {
           Pair("csig2", FieldsAre("isig2", "desc2", input2_path))));
 }
 
+TEST(GetCrashesFromWorkdirTest, FailsOnEmptyCrashSignatureIfEnvVarSet) {
+  TempDir test_dir;
+  const std::string workdir_path = test_dir.path();
+  WorkDir workdir{workdir_path, "binary_name", "binary_hash",
+                  /*my_shard_index=*/0};
+
+  const std::filesystem::path crashes =
+      workdir.CrashReproducerDirPaths().Shard(0);
+  const std::filesystem::path crash_metadata =
+      workdir.CrashMetadataDirPaths().Shard(0);
+  std::filesystem::create_directories(crashes);
+  std::filesystem::create_directories(crash_metadata);
+
+  auto input_path = SetContentsAndGetPath(crashes, "isig", "input");
+  SetContentsAndGetPath(crash_metadata, "isig.sig", "");
+  SetContentsAndGetPath(crash_metadata, "isig.desc", "desc");
+
+  setenv("FUZZTEST_FAIL_ON_EMPTY_CRASH_METADATA", "1", /*overwrite=*/1);
+  EXPECT_DEATH(GetCrashesFromWorkdir(workdir, /*total_shards=*/1),
+               "Empty crash signature");
+  unsetenv("FUZZTEST_FAIL_ON_EMPTY_CRASH_METADATA");
+}
+
+TEST(GetCrashesFromWorkdirTest, FailsOnEmptyCrashDescriptionIfEnvVarSet) {
+  TempDir test_dir;
+  const std::string workdir_path = test_dir.path();
+  WorkDir workdir{workdir_path, "binary_name", "binary_hash",
+                  /*my_shard_index=*/0};
+
+  const std::filesystem::path crashes =
+      workdir.CrashReproducerDirPaths().Shard(0);
+  const std::filesystem::path crash_metadata =
+      workdir.CrashMetadataDirPaths().Shard(0);
+  std::filesystem::create_directories(crashes);
+  std::filesystem::create_directories(crash_metadata);
+
+  auto input_path = SetContentsAndGetPath(crashes, "isig", "input");
+  SetContentsAndGetPath(crash_metadata, "isig.sig", "csig");
+  SetContentsAndGetPath(crash_metadata, "isig.desc", "");
+
+  setenv("FUZZTEST_FAIL_ON_EMPTY_CRASH_METADATA", "1", /*overwrite=*/1);
+  EXPECT_DEATH(GetCrashesFromWorkdir(workdir, /*total_shards=*/1),
+               "Empty crash description");
+  unsetenv("FUZZTEST_FAIL_ON_EMPTY_CRASH_METADATA");
+}
+
 class FakeCentipedeCallbacks : public CentipedeCallbacks {
  public:
   struct Crash {