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link/elf: fix parsing SHF_STRINGS section

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This commit is contained in:
Jakub Konka 2024-04-19 00:10:43 +02:00
parent 63a40bff47
commit 2cc1623925
4 changed files with 36 additions and 43 deletions
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6
src/link/Elf.zig
View File

@ -1340,7 +1340,7 @@ pub fn flushModule(self: *Elf, arena: Allocator, prog_node: *std.Progress.Node)
};
try self.addCommentString();
try self.sortMergeSections();
try self.finalizeMergeSections();
try self.initOutputSections();
try self.addLinkerDefinedSymbols();
self.claimUnresolved();
@ -3369,9 +3369,9 @@ pub fn resolveMergeSections(self: *Elf) !void {
if (has_errors) return error.FlushFailure;
}
pub fn sortMergeSections(self: *Elf) !void {
pub fn finalizeMergeSections(self: *Elf) !void {
for (self.merge_sections.items) |*msec| {
try msec.sort(self);
try msec.finalize(self);
}
}

59
src/link/Elf/Object.zig
View File

@ -683,39 +683,40 @@ pub fn initMergeSections(self: *Object, elf_file: *Elf) !void {
const data = try self.codeDecompressAlloc(elf_file, atom_index);
defer gpa.free(data);
const sh_entsize: u32 = @intCast(shdr.sh_entsize);
if (shdr.sh_flags & elf.SHF_STRINGS != 0) {
var pos: u32 = 0;
while (pos < data.len) switch (sh_entsize) {
0, 1 => {
// According to mold's source code, GHC emits MS sections with sh_entsize = 0.
// This actually can also happen for output created with `-r` mode.
const string = mem.sliceTo(@as([*:0]const u8, @ptrCast(data.ptr + pos)), 0);
if (pos + string.len == data.len) {
var err = try elf_file.addErrorWithNotes(1);
try err.addMsg(elf_file, "string not null terminated", .{});
try err.addNote(elf_file, "in {}:{s}", .{ self.fmtPath(), atom_ptr.name(elf_file) });
return error.MalformedObject;
}
try imsec.insertZ(gpa, string);
try imsec.offsets.append(gpa, pos);
pos += @as(u32, @intCast(string.len)) + 1; // account for null
},
else => |entsize| {
const string = data.ptr[pos..][0..entsize];
if (string[string.len - 1] != 0) {
var err = try elf_file.addErrorWithNotes(1);
try err.addMsg(elf_file, "string not null terminated", .{});
try err.addNote(elf_file, "in {}:{s}", .{ self.fmtPath(), atom_ptr.name(elf_file) });
return error.MalformedObject;
}
try imsec.insert(gpa, string);
try imsec.offsets.append(gpa, pos);
pos += @as(u32, @intCast(string.len));
},
const sh_entsize: u32 = switch (shdr.sh_entsize) {
// According to mold's source code, GHC emits MS sections with sh_entsize = 0.
// This actually can also happen for output created with `-r` mode.
0 => 1,
else => |x| @intCast(x),
};
const isNull = struct {
fn isNull(slice: []u8) bool {
for (slice) |x| if (x != 0) return false;
return true;
}
}.isNull;
var start: u32 = 0;
while (start < data.len) {
var end = start;
while (end < data.len - sh_entsize and !isNull(data[end .. end + sh_entsize])) : (end += sh_entsize) {}
if (!isNull(data[end .. end + sh_entsize])) {
var err = try elf_file.addErrorWithNotes(1);
try err.addMsg(elf_file, "string not null terminated", .{});
try err.addNote(elf_file, "in {}:{s}", .{ self.fmtPath(), atom_ptr.name(elf_file) });
return error.MalformedObject;
}
end += sh_entsize;
const string = data[start..end];
try imsec.insert(gpa, string);
try imsec.offsets.append(gpa, start);
start = end;
}
} else {
const sh_entsize: u32 = @intCast(shdr.sh_entsize);
if (sh_entsize == 0) continue; // Malformed, don't split but don't error out
if (shdr.sh_size % sh_entsize != 0) {
var err = try elf_file.addErrorWithNotes(1);

12
src/link/Elf/merge_section.zig
View File

@ -56,9 +56,9 @@ pub const MergeSection = struct {
return msec.insert(allocator, with_null);
}
/// Finalizes the merge section and clears hash table.
/// Sorts all owned subsections.
/// Clears string table.
pub fn sort(msec: *MergeSection, elf_file: *Elf) !void {
pub fn finalize(msec: *MergeSection, elf_file: *Elf) !void {
const gpa = elf_file.base.comp.gpa;
try msec.subsections.ensureTotalCapacityPrecise(gpa, msec.table.count());
@ -270,14 +270,6 @@ pub const InputMergeSection = struct {
try imsec.strings.append(allocator, .{ .pos = index, .len = @intCast(string.len) });
}
pub fn insertZ(imsec: *InputMergeSection, allocator: Allocator, string: []const u8) !void {
const index: u32 = @intCast(imsec.bytes.items.len);
try imsec.bytes.ensureUnusedCapacity(allocator, string.len + 1);
imsec.bytes.appendSliceAssumeCapacity(string);
imsec.bytes.appendAssumeCapacity(0);
try imsec.strings.append(allocator, .{ .pos = index, .len = @intCast(string.len + 1) });
}
pub const Index = u32;
};

2
src/link/Elf/relocatable.zig
View File

@ -181,7 +181,7 @@ pub fn flushObject(elf_file: *Elf, comp: *Compilation, module_obj_path: ?[]const
elf_file.markEhFrameAtomsDead();
try elf_file.resolveMergeSections();
try elf_file.addCommentString();
try elf_file.sortMergeSections();
try elf_file.finalizeMergeSections();
claimUnresolved(elf_file);
try initSections(elf_file);