zig

commit 406c85f9ba056e10899feed18dae91e20942dc55 (tree)
parent 062ddb693f3b060a59bc3881cbc6cea2cc8e2855
Author: Jakub Konka <kubkon@jakubkonka.com>
Date:   Sat, 22 Jan 2022 08:47:04 +0100

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)`.

Diffstat:
M
src/link/Elf.zig
 | 
2
+-
M
src/link/MachO.zig
 | 
2
+-

2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/link/Elf.zig b/src/link/Elf.zig
@@ -2118,7 +2118,7 @@ fn allocateTextBlock(self: *Elf, block_list: *TextBlockList, text_block: *TextBl
             const sym = self.local_symbols.items[big_block.local_sym_index];
             const capacity = big_block.capacity(self.*);
             const ideal_capacity = padToIdeal(capacity);
-            const ideal_capacity_end_vaddr = sym.st_value + ideal_capacity;
+            const ideal_capacity_end_vaddr = std.math.add(u64, sym.st_value, ideal_capacity) catch ideal_capacity;
             const capacity_end_vaddr = sym.st_value + capacity;
             const new_start_vaddr_unaligned = capacity_end_vaddr - new_block_ideal_capacity;
             const new_start_vaddr = mem.alignBackwardGeneric(u64, new_start_vaddr_unaligned, alignment);
diff --git a/src/link/MachO.zig b/src/link/MachO.zig
@@ -5064,7 +5064,7 @@ fn allocateAtom(self: *MachO, atom: *Atom, new_atom_size: u64, alignment: u64, m
             const sym = self.locals.items[big_atom.local_sym_index];
             const capacity = big_atom.capacity(self.*);
             const ideal_capacity = if (needs_padding) padToIdeal(capacity) else capacity;
-            const ideal_capacity_end_vaddr = sym.n_value + ideal_capacity;
+            const ideal_capacity_end_vaddr = math.add(u64, sym.n_value, ideal_capacity) catch ideal_capacity;
             const capacity_end_vaddr = sym.n_value + capacity;
             const new_start_vaddr_unaligned = capacity_end_vaddr - new_atom_ideal_capacity;
             const new_start_vaddr = mem.alignBackwardGeneric(u64, new_start_vaddr_unaligned, alignment);