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elf: check symtab section headers size when writing globals

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Without this, it may happen we write the globals without extending
the symtab section header's size. This can potentially lead to
clobbering some data in the file, or simply omitting the globals
from the symtab when displaying with support tooling such as `readelf`.
This commit is contained in:
Jakub Konka 2022-04-14 15:16:51 +02:00
parent 7a00227253
commit 4d77ef25f9
1 changed files with 16 additions and 0 deletions
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16
src/link/Elf.zig
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@ -2799,6 +2799,22 @@ fn writeAllGlobalSymbols(self: *Elf) !void {
.p32 => @sizeOf(elf.Elf32_Sym),
.p64 => @sizeOf(elf.Elf64_Sym),
};
const sym_align: u16 = switch (self.ptr_width) {
.p32 => @alignOf(elf.Elf32_Sym),
.p64 => @alignOf(elf.Elf64_Sym),
};
const needed_size = (self.local_symbols.items.len + self.global_symbols.items.len) * sym_size;
if (needed_size > self.allocatedSize(syms_sect.sh_offset)) {
// Move all the symbols to a new file location.
const new_offset = self.findFreeSpace(needed_size, sym_align);
const existing_size = @as(u64, syms_sect.sh_info) * sym_size;
const amt = try self.base.file.?.copyRangeAll(syms_sect.sh_offset, self.base.file.?, new_offset, existing_size);
if (amt != existing_size) return error.InputOutput;
syms_sect.sh_offset = new_offset;
}
syms_sect.sh_size = needed_size; // anticipating adding the global symbols later
self.shdr_table_dirty = true; // TODO look into only writing one section
const foreign_endian = self.base.options.target.cpu.arch.endian() != builtin.cpu.arch.endian();
const global_syms_off = syms_sect.sh_offset + self.local_symbols.items.len * sym_size;
switch (self.ptr_width) {