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cleanup: guard module builder lifetime

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This commit is contained in:
Duncan Ogilvie
2026-05-12 14:39:33 +02:00
parent 072a768461
commit c539e55dd8
2 changed files with 84 additions and 8 deletions
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src/llvm-nanobind.cpp
+27 -8
View File
@@ -4529,13 +4529,16 @@ struct LLVMBuilderWrapper : NoMoveCopy {
LLVMBuilderRef m_ref = nullptr;
LLVMContextRef m_ctx_ref = nullptr;
std::shared_ptr<ValidityToken> m_context_token;
std::shared_ptr<ValidityToken> m_module_token;
std::shared_ptr<ValidityToken> m_token;
// Constructor with basic block (position at end)
LLVMBuilderWrapper(LLVMContextRef ctx,
std::shared_ptr<ValidityToken> context_token,
LLVMBasicBlockRef bb)
LLVMBasicBlockRef bb,
std::shared_ptr<ValidityToken> module_token = nullptr)
: m_ctx_ref(ctx), m_context_token(std::move(context_token)),
m_module_token(std::move(module_token)),
m_token(std::make_shared<ValidityToken>()) {
m_ref = LLVMCreateBuilderInContext(ctx);
LLVMPositionBuilderAtEnd(m_ref, bb);
@@ -4544,8 +4547,10 @@ struct LLVMBuilderWrapper : NoMoveCopy {
// Constructor with instruction (position before/after debug records)
LLVMBuilderWrapper(LLVMContextRef ctx,
std::shared_ptr<ValidityToken> context_token,
LLVMValueRef inst, bool before_dbg)
LLVMValueRef inst, bool before_dbg,
std::shared_ptr<ValidityToken> module_token = nullptr)
: m_ctx_ref(ctx), m_context_token(std::move(context_token)),
m_module_token(std::move(module_token)),
m_token(std::make_shared<ValidityToken>()) {
if (!LLVMIsAInstruction(inst))
throw LLVMAssertionError("Builder position requires an instruction");
@@ -4577,6 +4582,8 @@ struct LLVMBuilderWrapper : NoMoveCopy {
throw LLVMMemoryError("Builder has been disposed");
if (!m_context_token || !m_context_token->is_valid())
throw LLVMMemoryError("Builder used after context was destroyed");
if (m_module_token && !m_module_token->is_valid())
throw LLVMMemoryError("Builder used after module was disposed");
}
void dispose() {
@@ -5899,11 +5906,13 @@ struct LLVMModuleWrapper : NoMoveCopy {
// Borrowed wrappers don't dispose the module when destroyed.
static LLVMModuleWrapper *
create_borrowed(LLVMModuleRef mod, LLVMContextRef ctx,
std::shared_ptr<ValidityToken> context_token) {
std::shared_ptr<ValidityToken> context_token,
std::shared_ptr<ValidityToken> module_token = nullptr) {
auto *wrapper = new LLVMModuleWrapper();
wrapper->m_ref = mod;
wrapper->m_context_token = std::move(context_token);
wrapper->m_token = std::make_shared<ValidityToken>();
wrapper->m_token = module_token ? std::move(module_token)
: std::make_shared<ValidityToken>();
wrapper->m_ctx_ref = ctx;
wrapper->m_borrowed = true;
return wrapper;
@@ -5937,6 +5946,8 @@ struct LLVMModuleWrapper : NoMoveCopy {
void check_valid() const {
if (!m_ref)
throw LLVMMemoryError("Module has been disposed");
if (!m_token || !m_token->is_valid())
throw LLVMMemoryError("Module has been disposed");
if (!m_context_token || !m_context_token->is_valid())
throw LLVMMemoryError("Module used after context was destroyed");
}
@@ -7039,6 +7050,7 @@ struct LLVMModuleManager : NoMoveCopy {
struct LLVMBuilderManager : NoMoveCopy {
LLVMContextWrapper *m_context = nullptr;
std::shared_ptr<ValidityToken> m_context_token;
std::shared_ptr<ValidityToken> m_module_token;
std::unique_ptr<LLVMBuilderWrapper> m_builder;
bool m_entered = false;
bool m_disposed = false;
@@ -7059,18 +7071,22 @@ struct LLVMBuilderManager : NoMoveCopy {
throw LLVMMemoryError("Builder manager already entered");
if (!m_context)
throw LLVMMemoryError("No context provided");
// Check context token validity before dereferencing m_context
// Check context/module token validity before dereferencing saved IR refs.
if (!m_context_token || !m_context_token->is_valid())
throw LLVMMemoryError("Builder's context has been destroyed");
if (m_module_token && !m_module_token->is_valid())
throw LLVMMemoryError("Builder's module has been disposed");
m_context->check_valid();
// Create builder with position
if (m_initial_bb) {
m_builder = std::make_unique<LLVMBuilderWrapper>(
m_context->m_ref, m_context->m_token, *m_initial_bb);
m_context->m_ref, m_context->m_token, *m_initial_bb,
m_module_token);
} else if (m_initial_inst) {
m_builder = std::make_unique<LLVMBuilderWrapper>(
m_context->m_ref, m_context->m_token, *m_initial_inst, m_before_dbg);
m_context->m_ref, m_context->m_token, *m_initial_inst, m_before_dbg,
m_module_token);
} else {
throw LLVMMemoryError(
"Builder must be created with a position (BasicBlock or "
@@ -10630,6 +10646,7 @@ LLVMModuleWrapper::create_builder(const LLVMBasicBlockWrapper &bb) {
"create_builder requires a block belonging to this module");
}
auto manager = new LLVMBuilderManager(get_context());
manager->m_module_token = m_token;
manager->m_initial_bb = bb.m_ref;
return manager;
}
@@ -10653,6 +10670,7 @@ LLVMModuleWrapper::create_builder(const LLVMValueWrapper &inst,
"create_builder requires an instruction belonging to this module");
}
auto manager = new LLVMBuilderManager(get_context());
manager->m_module_token = m_token;
manager->m_initial_inst = inst.m_ref;
manager->m_before_dbg = before_dbg;
return manager;
@@ -10670,7 +10688,8 @@ inline LLVMModuleWrapper *LLVMBuilderWrapper::module() const {
if (!mod_ref)
throw LLVMAssertionError("Builder insertion function has no parent module");
LLVMContextRef ctx_ref = LLVMGetModuleContext(mod_ref);
return LLVMModuleWrapper::create_borrowed(mod_ref, ctx_ref, m_context_token);
return LLVMModuleWrapper::create_borrowed(mod_ref, ctx_ref, m_context_token,
m_module_token);
}
inline LLVMContextWrapper *LLVMBuilderWrapper::context() const {
tests/regressions/test_memory_module_builder_manager.py
+57
View File
@@ -0,0 +1,57 @@
"""
Regression for Module.create_builder lifetime guards.
Root cause: Module.create_builder() stores raw basic-block/instruction refs in a
BuilderManager. If the module was disposed before entering that manager, the
manager previously only checked the context token, then created a builder at a
freed IR position. Accessing the resulting builder could segfault. Borrowed
modules returned from Builder.module had the same missing module-token guard.
"""
import llvm
def expect_memory_error(fn, message_part: str) -> None:
try:
fn()
except llvm.LLVMMemoryError as exc:
assert message_part in str(exc), str(exc)
else:
raise AssertionError("expected LLVMMemoryError")
def test_module_create_builder_manager_rejects_disposed_module() -> None:
with llvm.create_context() as ctx:
with ctx.create_module("builder_lifetime") as mod:
fn_ty = ctx.types.function(ctx.types.void, [])
fn = mod.add_function("f", fn_ty)
bb = fn.append_basic_block("entry")
bb_manager = mod.create_builder(bb)
with mod.create_builder(bb) as builder:
ret = builder.ret_void()
inst_manager = mod.create_builder(ret)
expect_memory_error(bb_manager.__enter__, "module has been disposed")
expect_memory_error(inst_manager.__enter__, "module has been disposed")
def test_builder_module_borrow_rejects_disposed_module() -> None:
with llvm.create_context() as ctx:
with ctx.create_module("borrowed_builder_module") as mod:
fn_ty = ctx.types.function(ctx.types.void, [])
fn = mod.add_function("f", fn_ty)
bb = fn.append_basic_block("entry")
with mod.create_builder(bb) as builder:
borrowed = builder.module
assert borrowed == mod
expect_memory_error(lambda: borrowed.name, "Module has been disposed")
if __name__ == "__main__":
test_module_create_builder_manager_rejects_disposed_module()
print("test_module_create_builder_manager_rejects_disposed_module: PASSED")
test_builder_module_borrow_rejects_disposed_module()
print("test_builder_module_borrow_rejects_disposed_module: PASSED")