Commit 406c85f9ba056e10899feed18dae91e20942dc55 | zig

author	Jakub Konka <kubkon@jakubkonka.com> 2022-01-22 08:47:04+01:00
committer	Jakub Konka <kubkon@jakubkonka.com> 2022-01-22 08:50:01+01:00
log	406c85f9ba056e10899feed18dae91e20942dc55
tree	fbc6b204723691dfad10851137c7df67858d679b
parent	062ddb693f3b060a59bc3881cbc6cea2cc8e2855

macho+elf: fix integer overflow in allocateAtom

If there is a big atom available for re-use in the free list, and
it's the last atom in section, it's ideal capacity might span the
entire section in which case we do not want to calculate the actual
end VM addr of the symbol since it may overflow. Instead, we just take
the max capacity available as end VM addr estimate. In this case,
the max capacity equals `std.math.maxInt(u64)`.

2 files changed, 2 insertions(+), 2 deletions(-)

src
- link
  - Elf.zig
  - MachO.zig

src/link/Elf.zig+1-1

...	...	@@ -2118,7 +2118,7 @@ fn allocateTextBlock(self: Elf, block_list: TextBlockList, text_block: *TextBl
2118	2118	const sym = self.local_symbols.items[big_block.local_sym_index];
2119	2119	const capacity = big_block.capacity(self.*);
2120	2120	const ideal_capacity = padToIdeal(capacity);
2121		const ideal_capacity_end_vaddr = sym.st_value + ideal_capacity;
	2121	const ideal_capacity_end_vaddr = std.math.add(u64, sym.st_value, ideal_capacity) catch ideal_capacity;
2122	2122	const capacity_end_vaddr = sym.st_value + capacity;
2123	2123	const new_start_vaddr_unaligned = capacity_end_vaddr - new_block_ideal_capacity;
2124	2124	const new_start_vaddr = mem.alignBackwardGeneric(u64, new_start_vaddr_unaligned, alignment);

src/link/MachO.zig+1-1

...	...	@@ -5064,7 +5064,7 @@ fn allocateAtom(self: MachO, atom: Atom, new_atom_size: u64, alignment: u64, m
5064	5064	const sym = self.locals.items[big_atom.local_sym_index];
5065	5065	const capacity = big_atom.capacity(self.*);
5066	5066	const ideal_capacity = if (needs_padding) padToIdeal(capacity) else capacity;
5067		const ideal_capacity_end_vaddr = sym.n_value + ideal_capacity;
	5067	const ideal_capacity_end_vaddr = math.add(u64, sym.n_value, ideal_capacity) catch ideal_capacity;
5068	5068	const capacity_end_vaddr = sym.n_value + capacity;
5069	5069	const new_start_vaddr_unaligned = capacity_end_vaddr - new_atom_ideal_capacity;
5070	5070	const new_start_vaddr = mem.alignBackwardGeneric(u64, new_start_vaddr_unaligned, alignment);