Fix potential overflow of unsigned type in for loop (#6902)

Summary:
x.size() -1 or y - 1 can overflow to an extremely large value when x.size() pr y is 0 when they are unsigned type. The end condition of i in the for loop will be extremely large, potentially causes segment fault. Fix them.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6902

Test Plan: pass make asan_check

Reviewed By: ajkr

Differential Revision: D21843767

Pulled By: zhichao-cao

fbshipit-source-id: 5b8b88155ac5a93d86246d832e89905a783bb5a1

db/compaction/compaction_job.cc

@@ -542,7 +542,7 @@ void CompactionJob::GenSubcompactionBoundaries() {
     // Greedily add ranges to the subcompaction until the sum of the ranges'
     // sizes becomes >= the expected mean size of a subcompaction
     sum = 0;
-    for (size_t i = 0; i < ranges.size() - 1; i++) {
+    for (size_t i = 0; i + 1 < ranges.size(); i++) {
       sum += ranges[i].size;
       if (subcompactions == 1) {
         // If there's only one left to schedule then it goes to the end so no

db/compaction/compaction_picker_universal.cc

@@ -765,7 +765,7 @@ Compaction* UniversalCompactionBuilder::PickCompactionToReduceSizeAmp() {
   }
 
   // Skip files that are already being compacted
-  for (size_t loop = 0; loop < sorted_runs_.size() - 1; loop++) {
+  for (size_t loop = 0; loop + 1 < sorted_runs_.size(); loop++) {
     sr = &sorted_runs_[loop];
     if (!sr->being_compacted) {
       start_index = loop;  // Consider this as the first candidate.
@@ -793,7 +793,7 @@ Compaction* UniversalCompactionBuilder::PickCompactionToReduceSizeAmp() {
   }
 
   // keep adding up all the remaining files
-  for (size_t loop = start_index; loop < sorted_runs_.size() - 1; loop++) {
+  for (size_t loop = start_index; loop + 1 < sorted_runs_.size(); loop++) {
     sr = &sorted_runs_[loop];
     if (sr->being_compacted) {
       char file_num_buf[kFormatFileNumberBufSize];

db/db_basic_test.cc

@@ -1900,13 +1900,13 @@ TEST_F(DBBasicTest, GetAllKeyVersions) {
   ASSERT_EQ(kNumInserts + kNumDeletes + kNumUpdates, key_versions.size());
 
   // Check non-default column family
-  for (size_t i = 0; i != kNumInserts - 1; ++i) {
+  for (size_t i = 0; i + 1 != kNumInserts; ++i) {
     ASSERT_OK(Put(1, std::to_string(i), "value"));
   }
-  for (size_t i = 0; i != kNumUpdates - 1; ++i) {
+  for (size_t i = 0; i + 1 != kNumUpdates; ++i) {
     ASSERT_OK(Put(1, std::to_string(i), "value1"));
   }
-  for (size_t i = 0; i != kNumDeletes - 1; ++i) {
+  for (size_t i = 0; i + 1 != kNumDeletes; ++i) {
     ASSERT_OK(Delete(1, std::to_string(i)));
   }
   ASSERT_OK(ROCKSDB_NAMESPACE::GetAllKeyVersions(

db/db_block_cache_test.cc

@@ -187,7 +187,7 @@ TEST_F(DBBlockCacheTest, TestWithoutCompressedBlockCache) {
   Iterator* iter = nullptr;
 
   // Load blocks into cache.
-  for (size_t i = 0; i < kNumBlocks - 1; i++) {
+  for (size_t i = 0; i + 1 < kNumBlocks; i++) {
     iter = db_->NewIterator(read_options);
     iter->Seek(ToString(i));
     ASSERT_OK(iter->status());
@@ -209,12 +209,12 @@ TEST_F(DBBlockCacheTest, TestWithoutCompressedBlockCache) {
   iter = nullptr;
 
   // Release iterators and access cache again.
-  for (size_t i = 0; i < kNumBlocks - 1; i++) {
+  for (size_t i = 0; i + 1 < kNumBlocks; i++) {
     iterators[i].reset();
     CheckCacheCounters(options, 0, 0, 0, 0);
   }
   ASSERT_EQ(0, cache->GetPinnedUsage());
-  for (size_t i = 0; i < kNumBlocks - 1; i++) {
+  for (size_t i = 0; i + 1 < kNumBlocks; i++) {
     iter = db_->NewIterator(read_options);
     iter->Seek(ToString(i));
     ASSERT_OK(iter->status());
@@ -243,7 +243,7 @@ TEST_F(DBBlockCacheTest, TestWithCompressedBlockCache) {
   Iterator* iter = nullptr;
 
   // Load blocks into cache.
-  for (size_t i = 0; i < kNumBlocks - 1; i++) {
+  for (size_t i = 0; i + 1 < kNumBlocks; i++) {
     iter = db_->NewIterator(read_options);
     iter->Seek(ToString(i));
     ASSERT_OK(iter->status());

db/db_flush_test.cc

@@ -499,13 +499,13 @@ TEST_P(DBAtomicFlushTest, AtomicFlushTriggeredByMemTableFull) {
   TEST_SYNC_POINT(
       "DBAtomicFlushTest::AtomicFlushTriggeredByMemTableFull:BeforeCheck");
   if (options.atomic_flush) {
-    for (size_t i = 0; i != num_cfs - 1; ++i) {
+    for (size_t i = 0; i + 1 != num_cfs; ++i) {
       auto cfh = static_cast<ColumnFamilyHandleImpl*>(handles_[i]);
       ASSERT_EQ(0, cfh->cfd()->imm()->NumNotFlushed());
       ASSERT_TRUE(cfh->cfd()->mem()->IsEmpty());
     }
   } else {
-    for (size_t i = 0; i != num_cfs - 1; ++i) {
+    for (size_t i = 0; i + 1 != num_cfs; ++i) {
       auto cfh = static_cast<ColumnFamilyHandleImpl*>(handles_[i]);
       ASSERT_EQ(0, cfh->cfd()->imm()->NumNotFlushed());
       ASSERT_FALSE(cfh->cfd()->mem()->IsEmpty());

db/db_range_del_test.cc

@@ -189,7 +189,7 @@ TEST_F(DBRangeDelTest, MaxCompactionBytesCutsOutputFiles) {
   std::vector<std::vector<FileMetaData>> files;
   dbfull()->TEST_GetFilesMetaData(db_->DefaultColumnFamily(), &files);
 
-  for (size_t i = 0; i < files[1].size() - 1; ++i) {
+  for (size_t i = 0; i + 1 < files[1].size(); ++i) {
     ASSERT_TRUE(InternalKeyComparator(opts.comparator)
                     .Compare(files[1][i].largest, files[1][i + 1].smallest) <
                 0);

db/external_sst_file_ingestion_job.cc

@@ -68,7 +68,7 @@ Status ExternalSstFileIngestionJob::Prepare(
                                    info2->smallest_internal_key) < 0;
         });
 
-    for (size_t i = 0; i < num_files - 1; i++) {
+    for (size_t i = 0; i + 1 < num_files; i++) {
       if (sstableKeyCompare(ucmp, sorted_files[i]->largest_internal_key,
                             sorted_files[i + 1]->smallest_internal_key) >= 0) {
         files_overlap_ = true;

db_stress_tool/db_stress_tool.cc

@@ -245,7 +245,7 @@ int db_stress_tool(int argc, char** argv) {
     }
   } else {
     uint64_t keys_per_level = key_gen_ctx.window / levels;
-    for (unsigned int level = 0; level < levels - 1; ++level) {
+    for (unsigned int level = 0; level + 1 < levels; ++level) {
       key_gen_ctx.weights.emplace_back(keys_per_level);
     }
     key_gen_ctx.weights.emplace_back(key_gen_ctx.window -

env/env_test.cc

@@ -1242,7 +1242,7 @@ TEST_F(EnvPosixTest, MultiReadNonAlignedLargeNum) {
     for (int so: start_offsets) {
       offsets.push_back(so);
     }
-    for (size_t i = 0; i < offsets.size() - 1; i++) {
+    for (size_t i = 0; i + 1 < offsets.size(); i++) {
       lens.push_back(static_cast<size_t>(rnd.Uniform(static_cast<int>(offsets[i + 1] - offsets[i])) + 1));
     }
     lens.push_back(static_cast<size_t>(rnd.Uniform(static_cast<int>(kTotalSize - offsets.back())) + 1));

table/cuckoo/cuckoo_table_builder_test.cc

@@ -110,7 +110,7 @@ class CuckooBuilderTest : public testing::Test {
     // Check contents of the bucket.
     std::vector<bool> keys_found(keys.size(), false);
     size_t bucket_size = expected_unused_bucket.size();
-    for (uint32_t i = 0; i < table_size + cuckoo_block_size - 1; ++i) {
+    for (uint32_t i = 0; i + 1 < table_size + cuckoo_block_size; ++i) {
       Slice read_slice;
       ASSERT_OK(file_reader->Read(IOOptions(), i * bucket_size, bucket_size,
                                   &read_slice, nullptr, nullptr));

util/coding_test.cc

@@ -161,7 +161,7 @@ TEST(Coding, Varint32Truncation) {
   std::string s;
   PutVarint32(&s, large_value);
   uint32_t result;
-  for (unsigned int len = 0; len < s.size() - 1; len++) {
+  for (unsigned int len = 0; len + 1 < s.size(); len++) {
     ASSERT_TRUE(GetVarint32Ptr(s.data(), s.data() + len, &result) == nullptr);
   }
   ASSERT_TRUE(
@@ -181,7 +181,7 @@ TEST(Coding, Varint64Truncation) {
   std::string s;
   PutVarint64(&s, large_value);
   uint64_t result;
-  for (unsigned int len = 0; len < s.size() - 1; len++) {
+  for (unsigned int len = 0; len + 1 < s.size(); len++) {
     ASSERT_TRUE(GetVarint64Ptr(s.data(), s.data() + len, &result) == nullptr);
   }
   ASSERT_TRUE(

utilities/blob_db/blob_dump_tool.cc

@@ -255,7 +255,7 @@ void BlobDumpTool::DumpSlice(const Slice s, DisplayType type) {
         snprintf(buf + j * 3 + 16, 2, "%x", c & 0xf);
         snprintf(buf + j + 65, 2, "%c", (0x20 <= c && c <= 0x7e) ? c : '.');
       }
-      for (size_t p = 0; p < sizeof(buf) - 1; p++) {
+      for (size_t p = 0; p + 1 < sizeof(buf); p++) {
         if (buf[p] == 0) {
           buf[p] = ' ';
         }

utilities/transactions/transaction_test.cc

@@ -722,7 +722,7 @@ TEST_P(TransactionStressTest, DeadlockCycle) {
     // We want the last transaction in the chain to block and hold everyone
     // back.
     std::vector<port::Thread> threads;
-    for (uint32_t i = 0; i < len - 1; i++) {
+    for (uint32_t i = 0; i + 1 < len; i++) {
       std::function<void()> blocking_thread = [&, i] {
         auto s = txns[i]->GetForUpdate(read_options, ToString(i + 1), nullptr);
         ASSERT_OK(s);

utilities/transactions/write_prepared_transaction_test.cc

@@ -1107,7 +1107,7 @@ TEST_P(WritePreparedTransactionTest, CheckAgainstSnapshots) {
                                       355l, 450l, 455l, 550l, 555l, 650l, 655l,
                                       750l, 755l, 850l, 855l, 950l, 955l};
   assert(seqs.size() > 1);
-  for (size_t i = 0; i < seqs.size() - 1; i++) {
+  for (size_t i = 0; i + 1 < seqs.size(); i++) {
     wp_db->old_commit_map_empty_ = true;  // reset
     CommitEntry commit_entry = {seqs[i], seqs[i + 1]};
     wp_db->CheckAgainstSnapshots(commit_entry);