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std.heap.GeneralPurposeAllocator: check canary in free

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This commit is contained in:
Andrew Kelley
2025-02-04 23:12:55 -08:00
parent 8ff7481e82
commit 0e0f0c9625
1 changed files with 6 additions and 0 deletions
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6
lib/std/heap/general_purpose_allocator.zig
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@@ -162,6 +162,10 @@ pub const Config = struct {
/// Tell whether the backing allocator returns already-zeroed memory.
backing_allocator_zeroes: bool = true,
/// Magic value that distinguishes allocations owned by this allocator from
/// other regions of memory.
canary: usize = @truncate(0x9232a6ff85dff10f),
};
pub const Check = enum { ok, leak };
@@ -266,6 +270,7 @@ pub fn GeneralPurposeAllocator(comptime config: Config) type {
allocated_count: SlotIndex,
freed_count: SlotIndex,
prev: ?*BucketHeader,
canary: usize = config.canary,
fn fromPage(page_addr: usize, slot_count: usize) *BucketHeader {
const unaligned = page_addr + page_size - bucketSize(slot_count);
@@ -832,6 +837,7 @@ pub fn GeneralPurposeAllocator(comptime config: Config) type {
const freed_addr = @intFromPtr(old_memory.ptr);
const page_addr = freed_addr & ~(page_size - 1);
const bucket: *BucketHeader = .fromPage(page_addr, slot_count);
if (bucket.canary != config.canary) @panic("Invalid free");
const page_offset = freed_addr - page_addr;
const size_class = @as(usize, 1) << @as(u6, @intCast(size_class_index));
const slot_index: SlotIndex = @intCast(page_offset / size_class);