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[lld/mac] Fix issues around thin archives

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- most importantly, fix a use-after-free when using thin archives,
  by putting the archive unique_ptr to the arena allocator. This
  ports D65565 to MachO

- correctly demangle symbol namess from archives in diagnostics

- add a test for thin archives -- it finds this UaF, but only when
  running it under asan (it also finds the demangling fix)

- make forceLoadArchive() use addFile() with a bool to have the archive
  loading code in fewer places. no behavior change; matches COFF port a
  bit better

Differential Revision: https://reviews.llvm.org/D92360
This commit is contained in:
Nico Weber 2020-11-20 10:14:57 -05:00
parent 19bdc8e5a3
commit 07ab597bb0
5 changed files with 80 additions and 30 deletions
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39
lld/MachO/Driver.cpp
View File

@ -225,10 +225,12 @@ static std::vector<ArchiveMember> getArchiveMembers(MemoryBufferRef mb) {
std::unique_ptr<Archive> file =
CHECK(Archive::create(mb),
mb.getBufferIdentifier() + ": failed to parse archive");
Archive *archive = file.get();
make<std::unique_ptr<Archive>>(std::move(file)); // take ownership
std::vector<ArchiveMember> v;
Error err = Error::success();
for (const Archive::Child &c : file->children(err)) {
for (const Archive::Child &c : archive->children(err)) {
MemoryBufferRef mbref =
CHECK(c.getMemoryBufferRef(),
mb.getBufferIdentifier() +
@ -246,17 +248,7 @@ static std::vector<ArchiveMember> getArchiveMembers(MemoryBufferRef mb) {
return v;
}
static void forceLoadArchive(StringRef path) {
if (Optional<MemoryBufferRef> buffer = readFile(path)) {
for (const ArchiveMember &member : getArchiveMembers(*buffer)) {
auto file = make<ObjFile>(member.mbref, member.modTime);
file->archiveName = buffer->getBufferIdentifier();
inputFiles.push_back(file);
}
}
}
static InputFile *addFile(StringRef path) {
static InputFile *addFile(StringRef path, bool forceLoadArchive) {
Optional<MemoryBufferRef> buffer = readFile(path);
if (!buffer)
return nullptr;
@ -271,8 +263,14 @@ static InputFile *addFile(StringRef path) {
if (!file->isEmpty() && !file->hasSymbolTable())
error(path + ": archive has no index; run ranlib to add one");
if (config->allLoad) {
forceLoadArchive(path);
if (config->allLoad || forceLoadArchive) {
if (Optional<MemoryBufferRef> buffer = readFile(path)) {
for (const ArchiveMember &member : getArchiveMembers(*buffer)) {
auto file = make<ObjFile>(member.mbref, member.modTime);
file->archiveName = buffer->getBufferIdentifier();
inputFiles.push_back(file);
}
}
} else if (config->forceLoadObjC) {
for (const object::Archive::Symbol &sym : file->symbols())
if (sym.getName().startswith(objc::klass))
@ -320,7 +318,7 @@ static void addFileList(StringRef path) {
return;
MemoryBufferRef mbref = *buffer;
for (StringRef path : args::getLines(mbref))
addFile(path);
addFile(path, false);
}
static std::array<StringRef, 6> archNames{"arm", "arm64", "i386",
@ -671,10 +669,11 @@ bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
// TODO: are any of these better handled via filtered() or getLastArg()?
switch (opt.getID()) {
case OPT_INPUT:
addFile(arg->getValue());
addFile(arg->getValue(), false);
break;
case OPT_weak_library: {
auto *dylibFile = dyn_cast_or_null<DylibFile>(addFile(arg->getValue()));
auto *dylibFile =
dyn_cast_or_null<DylibFile>(addFile(arg->getValue(), false));
if (dylibFile)
dylibFile->forceWeakImport = true;
break;
@ -683,13 +682,13 @@ bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
addFileList(arg->getValue());
break;
case OPT_force_load:
forceLoadArchive(arg->getValue());
addFile(arg->getValue(), true);
break;
case OPT_l:
case OPT_weak_l: {
StringRef name = arg->getValue();
if (Optional<std::string> path = findLibrary(name)) {
auto *dylibFile = dyn_cast_or_null<DylibFile>(addFile(*path));
auto *dylibFile = dyn_cast_or_null<DylibFile>(addFile(*path, false));
if (opt.getID() == OPT_weak_l && dylibFile)
dylibFile->forceWeakImport = true;
break;
@ -701,7 +700,7 @@ bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
case OPT_weak_framework: {
StringRef name = arg->getValue();
if (Optional<std::string> path = findFramework(name)) {
auto *dylibFile = dyn_cast_or_null<DylibFile>(addFile(*path));
auto *dylibFile = dyn_cast_or_null<DylibFile>(addFile(*path, false));
if (opt.getID() == OPT_weak_framework && dylibFile)
dylibFile->forceWeakImport = true;
break;

6
lld/MachO/InputFiles.cpp
View File

@ -584,7 +584,7 @@ void ArchiveFile::fetch(const object::Archive::Symbol &sym) {
object::Archive::Child c =
CHECK(sym.getMember(), toString(this) +
": could not get the member for symbol " +
sym.getName());
toMachOString(sym));
if (!seen.insert(c.getChildOffset()).second)
return;
@ -593,13 +593,13 @@ void ArchiveFile::fetch(const object::Archive::Symbol &sym) {
CHECK(c.getMemoryBufferRef(),
toString(this) +
": could not get the buffer for the member defining symbol " +
sym.getName());
toMachOString(sym));
uint32_t modTime = toTimeT(
CHECK(c.getLastModified(), toString(this) +
": could not get the modification time "
"for the member defining symbol " +
sym.getName()));
toMachOString(sym)));
auto file = make<ObjFile>(mb, modTime);
file->archiveName = getName();

22
lld/MachO/Symbols.cpp
View File

@ -14,6 +14,21 @@ using namespace llvm;
using namespace lld;
using namespace lld::macho;
// Returns a symbol for an error message.
static std::string demangle(StringRef symName) {
if (config->demangle)
return demangleItanium(symName);
return std::string(symName);
}
std::string lld::toString(const Symbol &sym) {
return demangle(sym.getName());
}
std::string lld::toMachOString(const object::Archive::Symbol &b) {
return demangle(b.getName());
}
uint64_t Defined::getVA() const {
if (isAbsolute())
return value;
@ -31,13 +46,6 @@ uint64_t Defined::getFileOffset() const {
void LazySymbol::fetchArchiveMember() { file->fetch(sym); }
// Returns a symbol for an error message.
std::string lld::toString(const Symbol &sym) {
if (config->demangle)
return demangleItanium(sym.getName());
return std::string(sym.getName());
}
uint64_t DSOHandle::getVA() const { return header->addr; }
uint64_t DSOHandle::getFileOffset() const { return header->fileOff; }

2
lld/MachO/Symbols.h
View File

@ -235,6 +235,8 @@ T *replaceSymbol(Symbol *s, ArgT &&... arg) {
} // namespace macho
std::string toString(const macho::Symbol &);
std::string toMachOString(const llvm::object::Archive::Symbol &);
} // namespace lld
#endif

41
lld/test/MachO/thin-archive.s Normal file
View File

@ -0,0 +1,41 @@
# REQUIRES: x86
# RUN: split-file %s %t
# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos -o %t/main.o %t/main.s
# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos -o %t/lib.o \
# RUN: %t/mangled-symbol.s
# RUN: llvm-ar csr %t/lib.a %t/lib.o
# RUN: llvm-ar csrT %t/lib_thin.a %t/lib.o
# RUN: %lld %t/main.o %t/lib.a -o %t/out
# RUN: llvm-nm %t/out
# RUN: %lld %t/main.o %t/lib_thin.a -o %t/out
# RUN: llvm-nm %t/out
# RUN: %lld /%t/main.o -force_load %t/lib_thin.a -o %t/out
# RUN: llvm-nm %t/out
# RUN: rm %t/lib.o
# RUN: %lld %t/main.o %t/lib.a -o %t/out
# RUN: llvm-nm %t/out
# RUN: not %lld %t/main.o %t/lib_thin.a -demangle -o %t/out 2>&1 | \
# RUN: FileCheck --check-prefix=NOOBJ %s
# RUN: not %lld %t/main.o %t/lib_thin.a -o %t/out 2>&1 | \
# RUN: FileCheck --check-prefix=NOOBJNODEMANGLE %s
# CHECK: __Z1fv
# CHECK: _main
# NOOBJ: error: {{.*}}lib_thin.a: could not get the buffer for the member defining symbol f(): '{{.*}}lib.o':
# NOOBJNODEMANGLE: error: {{.*}}lib_thin.a: could not get the buffer for the member defining symbol __Z1fv: '{{.*}}lib.o':
#--- mangled-symbol.s
.globl __Z1fv
__Z1fv:
retq
#--- main.s
.global _main
_main:
callq __Z1fv
mov $0, %rax
retq