From: Timmons C. Player <[email protected]>
Committer: Nadav Har'El <[email protected]>
Branch: master
memory: respect _bitset length bounds in page_range_allocator
The page_range_allocator attempts to merge neighbor page ranges
when a page range is freed in order to minimize memory fragmentation.
However, the original implementation didn't validate indexes before
checking the _bitset to determine whether a page range had a neighbor
or not. This change make sure that indexes stay within bounds.
This is the correct fix for the fix attempted in
44f8324e3f2e53f55022a1d93c8b072514e7ac07
Signed-off-by: Timmons C. Player <[email protected]>
Message-Id: <[email protected]>
---
diff --git a/core/mempool.cc b/core/mempool.cc
--- a/core/mempool.cc
+++ b/core/mempool.cc
@@ -761,13 +761,15 @@ page_range*
page_range_allocator::alloc_aligned(size_t size, size_t offset,
void page_range_allocator::free(page_range* pr)
{
- if (_bitmap[get_bitmap_idx(*pr) - 1]) {
+ auto idx = get_bitmap_idx(*pr);
+ if (idx && _bitmap[idx - 1]) {
auto pr2 = *(reinterpret_cast<page_range**>(pr) - 1);
remove(*pr2);
pr2->size += pr->size;
pr = pr2;
}
- if (_bitmap[get_bitmap_idx(*pr) + pr->size / page_size - 1]) {
+ auto next_idx = get_bitmap_idx(*pr) + pr->size / page_size;
+ if (next_idx < _bitmap.size() && _bitmap[next_idx]) {
auto pr2 = static_cast<page_range*>(static_cast<void*>(pr) +
pr->size);
remove(*pr2);
pr->size += pr2->size;
--
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