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DebugAllocator: Fix bucket removal logic causing segfault/leak (#23390)

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Make buckets doubly linked
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Auguste Rame 2025-04-02 08:15:04 -04:00 committed by Alex Rønne Petersen
parent ceb84c647b
commit 0b4176891c
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1 changed files with 16 additions and 2 deletions
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18
lib/std/heap/debug_allocator.zig
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@ -281,6 +281,7 @@ pub fn DebugAllocator(comptime config: Config) type {
allocated_count: SlotIndex,
freed_count: SlotIndex,
prev: ?*BucketHeader,
next: ?*BucketHeader,
canary: usize = config.canary,
fn fromPage(page_addr: usize, slot_count: usize) *BucketHeader {
@ -782,7 +783,11 @@ pub fn DebugAllocator(comptime config: Config) type {
.allocated_count = 1,
.freed_count = 0,
.prev = self.buckets[size_class_index],
.next = null,
};
if (self.buckets[size_class_index]) |old_head| {
old_head.next = bucket;
}
self.buckets[size_class_index] = bucket;
if (!config.backing_allocator_zeroes) {
@ -935,9 +940,18 @@ pub fn DebugAllocator(comptime config: Config) type {
}
bucket.freed_count += 1;
if (bucket.freed_count == bucket.allocated_count) {
if (self.buckets[size_class_index] == bucket) {
self.buckets[size_class_index] = null;
if (bucket.prev) |prev| {
prev.next = bucket.next;
}
if (bucket.next) |next| {
assert(self.buckets[size_class_index] != bucket);
next.prev = bucket.prev;
} else {
assert(self.buckets[size_class_index] == bucket);
self.buckets[size_class_index] = bucket.prev;
}
if (!config.never_unmap) {
const page: [*]align(page_size) u8 = @ptrFromInt(page_addr);
self.backing_allocator.rawFree(page[0..page_size], page_align, @returnAddress());