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Fix Forward Iterator Seek()/SeekToFirst()

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Summary:
In ForwardIterator::SeekInternal(), we may end up passing empty Slice representing an internal key to InternalKeyComparator::Compare.
and when we try to extract the user key from this empty Slice, we will create a slice with size = 0 - 8 ( which will overflow and cause us to read invalid memory as well )

Scenarios to reproduce these issues are in the unit tests
Closes https://github.com/facebook/rocksdb/pull/1467

Differential Revision: D4136660

Pulled By: lightmark

fbshipit-source-id: 151e128
This commit is contained in:
Islam AbdelRahman 2016-11-08 13:44:38 -08:00 committed by Facebook Github Bot
parent e48f3f8b9e
commit 193221e0a1
2 changed files with 61 additions and 3 deletions
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52
db/db_tailing_iter_test.cc
View File

@ -752,6 +752,58 @@ TEST_F(DBTestTailingIterator, ForwardIteratorVersionProperty) {
}
ASSERT_EQ(v3, v4);
}
TEST_F(DBTestTailingIterator, SeekWithUpperBoundBug) {
ReadOptions read_options;
read_options.tailing = true;
const Slice upper_bound("cc", 3);
read_options.iterate_upper_bound = &upper_bound;
// 1st L0 file
ASSERT_OK(db_->Put(WriteOptions(), "aa", "SEEN"));
ASSERT_OK(Flush());
// 2nd L0 file
ASSERT_OK(db_->Put(WriteOptions(), "zz", "NOT-SEEN"));
ASSERT_OK(Flush());
std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
iter->Seek("aa");
ASSERT_TRUE(iter->Valid());
ASSERT_EQ(iter->key().ToString(), "aa");
}
TEST_F(DBTestTailingIterator, SeekToFirstWithUpperBoundBug) {
ReadOptions read_options;
read_options.tailing = true;
const Slice upper_bound("cc", 3);
read_options.iterate_upper_bound = &upper_bound;
// 1st L0 file
ASSERT_OK(db_->Put(WriteOptions(), "aa", "SEEN"));
ASSERT_OK(Flush());
// 2nd L0 file
ASSERT_OK(db_->Put(WriteOptions(), "zz", "NOT-SEEN"));
ASSERT_OK(Flush());
std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
iter->SeekToFirst();
ASSERT_TRUE(iter->Valid());
ASSERT_EQ(iter->key().ToString(), "aa");
iter->Next();
ASSERT_FALSE(iter->Valid());
iter->SeekToFirst();
ASSERT_TRUE(iter->Valid());
ASSERT_EQ(iter->key().ToString(), "aa");
}
} // namespace rocksdb
#endif // !defined(ROCKSDB_LITE)

12
db/forward_iterator.cc
View File

@ -296,9 +296,15 @@ void ForwardIterator::SeekInternal(const Slice& internal_key,
// an option to turn it off.
if (seek_to_first || NeedToSeekImmutable(internal_key)) {
immutable_status_ = Status::OK();
if ((has_iter_trimmed_for_upper_bound_) &&
(cfd_->internal_comparator().InternalKeyComparator::Compare(
prev_key_.GetKey(), internal_key) > 0)) {
if (has_iter_trimmed_for_upper_bound_ &&
(
// prev_ is not set yet
is_prev_set_ == false ||
// We are doing SeekToFirst() and internal_key.size() = 0
seek_to_first ||
// prev_key_ > internal_key
cfd_->internal_comparator().InternalKeyComparator::Compare(
prev_key_.GetKey(), internal_key) > 0)) {
// Some iterators are trimmed. Need to rebuild.
RebuildIterators(true);
// Already seeked mutable iter, so seek again