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WasmAllocator: fix safety panic during OOM

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This commit is contained in:
Jacob Young 2024-03-23 03:38:51 +01:00
parent ff7ca4b70f
commit a7282d0910
1 changed files with 8 additions and 10 deletions
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18
lib/std/heap/WasmAllocator.zig
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@ -55,7 +55,7 @@ fn alloc(ctx: *anyopaque, len: usize, log2_align: u8, return_address: usize) ?[*
const addr = a: { const addr = a: {
const top_free_ptr = frees[class]; const top_free_ptr = frees[class];
if (top_free_ptr != 0) { if (top_free_ptr != 0) {
const node = @as(*usize, @ptrFromInt(top_free_ptr + (slot_size - @sizeOf(usize)))); const node: *usize = @ptrFromInt(top_free_ptr + (slot_size - @sizeOf(usize)));
frees[class] = node.*; frees[class] = node.*;
break :a top_free_ptr; break :a top_free_ptr;
} }
@ -74,11 +74,10 @@ fn alloc(ctx: *anyopaque, len: usize, log2_align: u8, return_address: usize) ?[*
break :a next_addr; break :a next_addr;
} }
}; };
return @as([*]u8, @ptrFromInt(addr)); return @ptrFromInt(addr);
} }
const bigpages_needed = bigPagesNeeded(actual_len); const bigpages_needed = bigPagesNeeded(actual_len);
const addr = allocBigPages(bigpages_needed); return @ptrFromInt(allocBigPages(bigpages_needed));
return @as([*]u8, @ptrFromInt(addr));
} }
fn resize( fn resize(
@ -123,14 +122,14 @@ fn free(
const class = math.log2(slot_size) - min_class; const class = math.log2(slot_size) - min_class;
const addr = @intFromPtr(buf.ptr); const addr = @intFromPtr(buf.ptr);
if (class < size_class_count) { if (class < size_class_count) {
const node = @as(*usize, @ptrFromInt(addr + (slot_size - @sizeOf(usize)))); const node: *usize = @ptrFromInt(addr + (slot_size - @sizeOf(usize)));
node.* = frees[class]; node.* = frees[class];
frees[class] = addr; frees[class] = addr;
} else { } else {
const bigpages_needed = bigPagesNeeded(actual_len); const bigpages_needed = bigPagesNeeded(actual_len);
const pow2_pages = math.ceilPowerOfTwoAssert(usize, bigpages_needed); const pow2_pages = math.ceilPowerOfTwoAssert(usize, bigpages_needed);
const big_slot_size_bytes = pow2_pages * bigpage_size; const big_slot_size_bytes = pow2_pages * bigpage_size;
const node = @as(*usize, @ptrFromInt(addr + (big_slot_size_bytes - @sizeOf(usize)))); const node: *usize = @ptrFromInt(addr + (big_slot_size_bytes - @sizeOf(usize)));
const big_class = math.log2(pow2_pages); const big_class = math.log2(pow2_pages);
node.* = big_frees[big_class]; node.* = big_frees[big_class];
big_frees[big_class] = addr; big_frees[big_class] = addr;
@ -148,15 +147,14 @@ fn allocBigPages(n: usize) usize {
const top_free_ptr = big_frees[class]; const top_free_ptr = big_frees[class];
if (top_free_ptr != 0) { if (top_free_ptr != 0) {
const node = @as(*usize, @ptrFromInt(top_free_ptr + (slot_size_bytes - @sizeOf(usize)))); const node: *usize = @ptrFromInt(top_free_ptr + (slot_size_bytes - @sizeOf(usize)));
big_frees[class] = node.*; big_frees[class] = node.*;
return top_free_ptr; return top_free_ptr;
} }
const page_index = @wasmMemoryGrow(0, pow2_pages * pages_per_bigpage); const page_index = @wasmMemoryGrow(0, pow2_pages * pages_per_bigpage);
if (page_index <= 0) return 0; if (page_index == -1) return 0;
const addr = @as(u32, @intCast(page_index)) * wasm.page_size; return @as(usize, @intCast(page_index)) * wasm.page_size;
return addr;
} }
const test_ally = Allocator{ const test_ally = Allocator{