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AK: Clear OrderedHashTable previous/next pointers on removal

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With Clang, the previous/next pointers in buckets of an
`OrderedHashTable` are not cleared when a bucket is being shifted up as
a result of a removed bucket. As a result, an unfortunate pointer mixup
could lead to an infinite loop in the `HashTable` iterator, which was
exposed in `HashMap::keys()`.

Co-authored-by: Luke Wilde <lukew@serenityos.org>
This commit is contained in:
Jelle Raaijmakers 2023-03-15 18:37:55 +01:00
parent d16d805d96
commit 954d660094
2 changed files with 28 additions and 0 deletions
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4
AK/HashTable.h
View file

@ -690,6 +690,10 @@ private:
auto* shift_to_bucket = &m_buckets[shift_to_index];
*shift_to_bucket = move(*shift_from_bucket);
if constexpr (IsOrdered) {
shift_from_bucket->previous = nullptr;
shift_from_bucket->next = nullptr;
}
shift_to_bucket->state = bucket_state_for_probe_length(shift_from_probe_length - 1);
update_bucket_neighbours(shift_to_bucket);

24
Tests/AK/TestHashTable.cpp
View file

@ -410,3 +410,27 @@ TEST_CASE(ordered_remove_from_head)
EXPECT_EQ(map.size(), 0u);
}
TEST_CASE(ordered_infinite_loop_clang_regression)
{
OrderedHashTable<DeprecatedString> map;
map.set("");
map.set("1");
map.set("_cb");
map.set("2");
map.set("3");
map.set("_cb_svref");
map.set("_cb_svref_expires");
map.remove("_cb_svref");
map.remove("_cb_svref_expires");
map.set("_cb_svref");
size_t iterations = 0;
auto size = map.size();
for (auto it = map.begin(); it != map.end(); ++it) {
if (++iterations > size) {
VERIFY(false);
break;
}
}
}