authorgravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2019-02-14 01:09:33-05:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2019-02-14 01:09:33-05:00
log59de24817e8538434f35a20a401f40c2f0231a9a
tree7c06cd2749d2bb449742fc98dac59ab82a480b48
parentd4d2718bca9e23ceec029bb505c0ea1b91c875b6
signature Commit is signed but in an unrecognized format.

runtime safety check for casting null to pointer

see #1059

6 files changed, 67 insertions(+), 27 deletions(-)

src/all_types.hpp+3
......@@ -1488,6 +1488,7 @@ enum PanicMsgId {
14881488 PanicMsgIdBadUnionField,
14891489 PanicMsgIdBadEnumValue,
14901490 PanicMsgIdFloatToInt,
1491 PanicMsgIdPtrCastNull,
14911492
14921493 PanicMsgIdCount,
14931494};
......@@ -3001,12 +3002,14 @@ struct IrInstructionPtrCastSrc {
30013002
30023003 IrInstruction *dest_type;
30033004 IrInstruction *ptr;
3005 bool safety_check_on;
30043006};
30053007
30063008struct IrInstructionPtrCastGen {
30073009 IrInstruction base;
30083010
30093011 IrInstruction *ptr;
3012 bool safety_check_on;
30103013};
30113014
30123015struct IrInstructionBitCast {
src/analyze.cpp+9
......@@ -6902,3 +6902,12 @@ const char *container_string(ContainerKind kind) {
69026902 }
69036903 zig_unreachable();
69046904}
6905
6906bool ptr_allows_addr_zero(ZigType *ptr_type) {
6907 if (ptr_type->id == ZigTypeIdPointer) {
6908 return ptr_type->data.pointer.allow_zero;
6909 } else if (ptr_type->id == ZigTypeIdOptional) {
6910 return true;
6911 }
6912 return false;
6913}
src/analyze.hpp+1
......@@ -45,6 +45,7 @@ void find_libc_lib_path(CodeGen *g);
4545
4646bool type_has_bits(ZigType *type_entry);
4747bool type_allowed_in_extern(CodeGen *g, ZigType *type_entry);
48bool ptr_allows_addr_zero(ZigType *ptr_type);
4849
4950ImportTableEntry *add_source_file(CodeGen *g, PackageTableEntry *package, Buf *abs_full_path, Buf *source_code);
5051
src/codegen.cpp+18-1
......@@ -950,6 +950,8 @@ static Buf *panic_msg_buf(PanicMsgId msg_id) {
950950 return buf_create_from_str("invalid enum value");
951951 case PanicMsgIdFloatToInt:
952952 return buf_create_from_str("integer part of floating point value out of bounds");
953 case PanicMsgIdPtrCastNull:
954 return buf_create_from_str("cast causes pointer to be null");
953955 }
954956 zig_unreachable();
955957}
......@@ -3028,7 +3030,22 @@ static LLVMValueRef ir_render_ptr_cast(CodeGen *g, IrExecutable *executable,
30283030 return nullptr;
30293031 }
30303032 LLVMValueRef ptr = ir_llvm_value(g, instruction->ptr);
3031 return LLVMBuildBitCast(g->builder, ptr, wanted_type->type_ref, "");
3033 LLVMValueRef result_ptr = LLVMBuildBitCast(g->builder, ptr, wanted_type->type_ref, "");
3034 bool want_safety_check = instruction->safety_check_on && ir_want_runtime_safety(g, &instruction->base);
3035 if (!want_safety_check || ptr_allows_addr_zero(wanted_type))
3036 return result_ptr;
3037
3038 LLVMValueRef zero = LLVMConstNull(LLVMTypeOf(result_ptr));
3039 LLVMValueRef ok_bit = LLVMBuildICmp(g->builder, LLVMIntNE, result_ptr, zero, "");
3040 LLVMBasicBlockRef fail_block = LLVMAppendBasicBlock(g->cur_fn_val, "PtrCastFail");
3041 LLVMBasicBlockRef ok_block = LLVMAppendBasicBlock(g->cur_fn_val, "PtrCastOk");
3042 LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
3043
3044 LLVMPositionBuilderAtEnd(g->builder, fail_block);
3045 gen_safety_crash(g, PanicMsgIdPtrCastNull);
3046
3047 LLVMPositionBuilderAtEnd(g->builder, ok_block);
3048 return result_ptr;
30323049}
30333050
30343051static LLVMValueRef ir_render_bit_cast(CodeGen *g, IrExecutable *executable,
src/ir.cpp+26-26
......@@ -172,7 +172,7 @@ static void buf_write_value_bytes(CodeGen *codegen, uint8_t *buf, ConstExprValue
172172static Error ir_read_const_ptr(IrAnalyze *ira, CodeGen *codegen, AstNode *source_node,
173173 ConstExprValue *out_val, ConstExprValue *ptr_val);
174174static IrInstruction *ir_analyze_ptr_cast(IrAnalyze *ira, IrInstruction *source_instr, IrInstruction *ptr,
175 ZigType *dest_type, IrInstruction *dest_type_src);
175 ZigType *dest_type, IrInstruction *dest_type_src, bool safety_check_on);
176176static ConstExprValue *ir_resolve_const(IrAnalyze *ira, IrInstruction *value, UndefAllowed undef_allowed);
177177static void copy_const_val(ConstExprValue *dest, ConstExprValue *src, bool same_global_refs);
178178static Error resolve_ptr_align(IrAnalyze *ira, ZigType *ty, uint32_t *result_align);
......@@ -2202,12 +2202,13 @@ static IrInstruction *ir_build_test_comptime(IrBuilder *irb, Scope *scope, AstNo
22022202}
22032203
22042204static IrInstruction *ir_build_ptr_cast_src(IrBuilder *irb, Scope *scope, AstNode *source_node,
2205 IrInstruction *dest_type, IrInstruction *ptr)
2205 IrInstruction *dest_type, IrInstruction *ptr, bool safety_check_on)
22062206{
22072207 IrInstructionPtrCastSrc *instruction = ir_build_instruction<IrInstructionPtrCastSrc>(
22082208 irb, scope, source_node);
22092209 instruction->dest_type = dest_type;
22102210 instruction->ptr = ptr;
2211 instruction->safety_check_on = safety_check_on;
22112212
22122213 ir_ref_instruction(dest_type, irb->current_basic_block);
22132214 ir_ref_instruction(ptr, irb->current_basic_block);
......@@ -2216,12 +2217,13 @@ static IrInstruction *ir_build_ptr_cast_src(IrBuilder *irb, Scope *scope, AstNod
22162217}
22172218
22182219static IrInstruction *ir_build_ptr_cast_gen(IrAnalyze *ira, IrInstruction *source_instruction,
2219 ZigType *ptr_type, IrInstruction *ptr)
2220 ZigType *ptr_type, IrInstruction *ptr, bool safety_check_on)
22202221{
22212222 IrInstructionPtrCastGen *instruction = ir_build_instruction<IrInstructionPtrCastGen>(
22222223 &ira->new_irb, source_instruction->scope, source_instruction->source_node);
22232224 instruction->base.value.type = ptr_type;
22242225 instruction->ptr = ptr;
2226 instruction->safety_check_on = safety_check_on;
22252227
22262228 ir_ref_instruction(ptr, ira->new_irb.current_basic_block);
22272229
......@@ -4505,7 +4507,7 @@ static IrInstruction *ir_gen_builtin_fn_call(IrBuilder *irb, Scope *scope, AstNo
45054507 if (arg1_value == irb->codegen->invalid_instruction)
45064508 return arg1_value;
45074509
4508 IrInstruction *ptr_cast = ir_build_ptr_cast_src(irb, scope, node, arg0_value, arg1_value);
4510 IrInstruction *ptr_cast = ir_build_ptr_cast_src(irb, scope, node, arg0_value, arg1_value, true);
45094511 return ir_lval_wrap(irb, scope, ptr_cast, lval);
45104512 }
45114513 case BuiltinFnIdBitCast:
......@@ -6740,7 +6742,8 @@ static IrInstruction *ir_gen_cancel_target(IrBuilder *irb, Scope *scope, AstNode
67406742 IrInstruction *is_suspended_mask = ir_build_const_usize(irb, scope, node, 0x2); // 0b010
67416743
67426744 // TODO relies on Zig not re-ordering fields
6743 IrInstruction *casted_target_inst = ir_build_ptr_cast_src(irb, scope, node, promise_T_type_val, target_inst);
6745 IrInstruction *casted_target_inst = ir_build_ptr_cast_src(irb, scope, node, promise_T_type_val, target_inst,
6746 false);
67446747 IrInstruction *coro_promise_ptr = ir_build_coro_promise(irb, scope, node, casted_target_inst);
67456748 Buf *atomic_state_field_name = buf_create_from_str(ATOMIC_STATE_FIELD_NAME);
67466749 IrInstruction *atomic_state_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr,
......@@ -6818,7 +6821,8 @@ static IrInstruction *ir_gen_resume_target(IrBuilder *irb, Scope *scope, AstNode
68186821 get_promise_type(irb->codegen, irb->codegen->builtin_types.entry_void));
68196822
68206823 // TODO relies on Zig not re-ordering fields
6821 IrInstruction *casted_target_inst = ir_build_ptr_cast_src(irb, scope, node, promise_T_type_val, target_inst);
6824 IrInstruction *casted_target_inst = ir_build_ptr_cast_src(irb, scope, node, promise_T_type_val, target_inst,
6825 false);
68226826 IrInstruction *coro_promise_ptr = ir_build_coro_promise(irb, scope, node, casted_target_inst);
68236827 Buf *atomic_state_field_name = buf_create_from_str(ATOMIC_STATE_FIELD_NAME);
68246828 IrInstruction *atomic_state_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr,
......@@ -7363,7 +7367,8 @@ bool ir_gen(CodeGen *codegen, AstNode *node, Scope *scope, IrExecutable *ir_exec
73637367
73647368 u8_ptr_type = ir_build_const_type(irb, coro_scope, node,
73657369 get_pointer_to_type(irb->codegen, irb->codegen->builtin_types.entry_u8, false));
7366 IrInstruction *promise_as_u8_ptr = ir_build_ptr_cast_src(irb, coro_scope, node, u8_ptr_type, coro_promise_ptr);
7370 IrInstruction *promise_as_u8_ptr = ir_build_ptr_cast_src(irb, coro_scope, node, u8_ptr_type,
7371 coro_promise_ptr, false);
73677372 coro_id = ir_build_coro_id(irb, coro_scope, node, promise_as_u8_ptr);
73687373 coro_size_var = ir_create_var(irb, node, coro_scope, nullptr, false, false, true, const_bool_false);
73697374 IrInstruction *coro_size = ir_build_coro_size(irb, coro_scope, node);
......@@ -7387,7 +7392,8 @@ bool ir_gen(CodeGen *codegen, AstNode *node, Scope *scope, IrExecutable *ir_exec
73877392 ir_build_return(irb, coro_scope, node, undef);
73887393
73897394 ir_set_cursor_at_end_and_append_block(irb, alloc_ok_block);
7390 IrInstruction *coro_mem_ptr = ir_build_ptr_cast_src(irb, coro_scope, node, u8_ptr_type, maybe_coro_mem_ptr);
7395 IrInstruction *coro_mem_ptr = ir_build_ptr_cast_src(irb, coro_scope, node, u8_ptr_type, maybe_coro_mem_ptr,
7396 false);
73917397 irb->exec->coro_handle = ir_build_coro_begin(irb, coro_scope, node, coro_id, coro_mem_ptr);
73927398
73937399 Buf *atomic_state_field_name = buf_create_from_str(ATOMIC_STATE_FIELD_NAME);
......@@ -7465,9 +7471,10 @@ bool ir_gen(CodeGen *codegen, AstNode *node, Scope *scope, IrExecutable *ir_exec
74657471 get_pointer_to_type_extra(irb->codegen, irb->codegen->builtin_types.entry_u8,
74667472 false, false, PtrLenUnknown, 0, 0, 0));
74677473 IrInstruction *result_ptr = ir_build_load_ptr(irb, scope, node, irb->exec->coro_result_ptr_field_ptr);
7468 IrInstruction *result_ptr_as_u8_ptr = ir_build_ptr_cast_src(irb, scope, node, u8_ptr_type_unknown_len, result_ptr);
7469 IrInstruction *return_value_ptr_as_u8_ptr = ir_build_ptr_cast_src(irb, scope, node, u8_ptr_type_unknown_len,
7470 irb->exec->coro_result_field_ptr);
7474 IrInstruction *result_ptr_as_u8_ptr = ir_build_ptr_cast_src(irb, scope, node, u8_ptr_type_unknown_len,
7475 result_ptr, false);
7476 IrInstruction *return_value_ptr_as_u8_ptr = ir_build_ptr_cast_src(irb, scope, node,
7477 u8_ptr_type_unknown_len, irb->exec->coro_result_field_ptr, false);
74717478 IrInstruction *return_type_inst = ir_build_const_type(irb, scope, node,
74727479 fn_entry->type_entry->data.fn.fn_type_id.return_type);
74737480 IrInstruction *size_of_ret_val = ir_build_size_of(irb, scope, node, return_type_inst);
......@@ -7517,7 +7524,8 @@ bool ir_gen(CodeGen *codegen, AstNode *node, Scope *scope, IrExecutable *ir_exec
75177524 IrInstruction *u8_ptr_type_unknown_len = ir_build_const_type(irb, scope, node,
75187525 get_pointer_to_type_extra(irb->codegen, irb->codegen->builtin_types.entry_u8,
75197526 false, false, PtrLenUnknown, 0, 0, 0));
7520 IrInstruction *coro_mem_ptr = ir_build_ptr_cast_src(irb, scope, node, u8_ptr_type_unknown_len, coro_mem_ptr_maybe);
7527 IrInstruction *coro_mem_ptr = ir_build_ptr_cast_src(irb, scope, node, u8_ptr_type_unknown_len,
7528 coro_mem_ptr_maybe, false);
75217529 IrInstruction *coro_mem_ptr_ref = ir_build_ref(irb, scope, node, coro_mem_ptr, true, false);
75227530 IrInstruction *coro_size_ptr = ir_build_var_ptr(irb, scope, node, coro_size_var);
75237531 IrInstruction *coro_size = ir_build_load_ptr(irb, scope, node, coro_size_ptr);
......@@ -8644,15 +8652,6 @@ static ZigType *get_error_set_intersection(IrAnalyze *ira, ZigType *set1, ZigTyp
86448652 return err_set_type;
86458653}
86468654
8647static bool ptr_allows_addr_zero(ZigType *ptr_type) {
8648 if (ptr_type->id == ZigTypeIdPointer) {
8649 return ptr_type->data.pointer.allow_zero;
8650 } else if (ptr_type->id == ZigTypeIdOptional) {
8651 return true;
8652 }
8653 return false;
8654}
8655
86568655static ConstCastOnly types_match_const_cast_only(IrAnalyze *ira, ZigType *wanted_type,
86578656 ZigType *actual_type, AstNode *source_node, bool wanted_is_mutable)
86588657{
......@@ -11310,7 +11309,7 @@ static IrInstruction *ir_analyze_cast(IrAnalyze *ira, IrInstruction *source_inst
1131011309 actual_type->data.pointer.host_int_bytes == dest_ptr_type->data.pointer.host_int_bytes &&
1131111310 get_ptr_align(ira->codegen, actual_type) >= get_ptr_align(ira->codegen, dest_ptr_type))
1131211311 {
11313 return ir_analyze_ptr_cast(ira, source_instr, value, wanted_type, source_instr);
11312 return ir_analyze_ptr_cast(ira, source_instr, value, wanted_type, source_instr, true);
1131411313 }
1131511314 }
1131611315
......@@ -11352,7 +11351,7 @@ static IrInstruction *ir_analyze_cast(IrAnalyze *ira, IrInstruction *source_inst
1135211351 actual_type->data.pointer.child_type, source_node,
1135311352 !wanted_type->data.pointer.is_const).id == ConstCastResultIdOk)
1135411353 {
11355 return ir_analyze_ptr_cast(ira, source_instr, value, wanted_type, source_instr);
11354 return ir_analyze_ptr_cast(ira, source_instr, value, wanted_type, source_instr, true);
1135611355 }
1135711356
1135811357 // cast from integer to C pointer
......@@ -20616,7 +20615,7 @@ static IrInstruction *ir_align_cast(IrAnalyze *ira, IrInstruction *target, uint3
2061620615}
2061720616
2061820617static IrInstruction *ir_analyze_ptr_cast(IrAnalyze *ira, IrInstruction *source_instr, IrInstruction *ptr,
20619 ZigType *dest_type, IrInstruction *dest_type_src)
20618 ZigType *dest_type, IrInstruction *dest_type_src, bool safety_check_on)
2062020619{
2062120620 Error err;
2062220621
......@@ -20685,7 +20684,7 @@ static IrInstruction *ir_analyze_ptr_cast(IrAnalyze *ira, IrInstruction *source_
2068520684 return ira->codegen->invalid_instruction;
2068620685 }
2068720686
20688 IrInstruction *casted_ptr = ir_build_ptr_cast_gen(ira, source_instr, dest_type, ptr);
20687 IrInstruction *casted_ptr = ir_build_ptr_cast_gen(ira, source_instr, dest_type, ptr, safety_check_on);
2068920688
2069020689 if (type_has_bits(dest_type) && !type_has_bits(src_type)) {
2069120690 ErrorMsg *msg = ir_add_error(ira, source_instr,
......@@ -20722,7 +20721,8 @@ static IrInstruction *ir_analyze_instruction_ptr_cast(IrAnalyze *ira, IrInstruct
2072220721 if (type_is_invalid(src_type))
2072320722 return ira->codegen->invalid_instruction;
2072420723
20725 return ir_analyze_ptr_cast(ira, &instruction->base, ptr, dest_type, dest_type_value);
20724 return ir_analyze_ptr_cast(ira, &instruction->base, ptr, dest_type, dest_type_value,
20725 instruction->safety_check_on);
2072620726}
2072720727
2072820728static void buf_write_value_bytes_array(CodeGen *codegen, uint8_t *buf, ConstExprValue *val, size_t len) {
test/runtime_safety.zig+10
......@@ -1,6 +1,16 @@
11const tests = @import("tests.zig");
22
33pub fn addCases(cases: *tests.CompareOutputContext) void {
4 cases.addRuntimeSafety("pointer casting null to non-optional pointer",
5 \\pub fn panic(message: []const u8, stack_trace: ?*@import("builtin").StackTrace) noreturn {
6 \\ @import("std").os.exit(126);
7 \\}
8 \\pub fn main() void {
9 \\ var c_ptr: [*c]u8 = 0;
10 \\ var zig_ptr: *u8 = c_ptr;
11 \\}
12 );
13
414 cases.addRuntimeSafety("@intToEnum - no matching tag value",
515 \\pub fn panic(message: []const u8, stack_trace: ?*@import("builtin").StackTrace) noreturn {
616 \\ @import("std").os.exit(126);