与csc test.cs
:
(196c.1874): Access violation - code c0000005 (first chance)
mscorlib_ni!System.RuntimeType.GetConstructorImpl(System.Reflection.BindingFlags, System.Reflection.Binder, System.Reflection.CallingConventions, System.Type[], System.Reflection.ParameterModifier[])+0xa3:
000007fe`e5735403 488b4608 mov rax,qword ptr [rsi+8] ds:00000000`00000008=????????????????
尝试从[rsi+8]
when @rsi
为NULL 加载。让我们检查一下功能:
0:000> ln 000007fe`e5735403
(000007fe`e5735360) mscorlib_ni!System.RuntimeType.GetConstructorImpl(System.Reflection.BindingFlags, System.Reflection.Binder, System.Reflection.CallingConventions, System.Type[], System.Reflection.ParameterModifier[])+0xa3
0:000> uf 000007fe`e5735360
Flow analysis was incomplete, some code may be missing
mscorlib_ni!System.RuntimeType.GetConstructorImpl(System.Reflection.BindingFlags, System.Reflection.Binder, System.Reflection.CallingConventions, System.Type[], System.Reflection.ParameterModifier[]):
000007fe`e5735360 53 push rbx
000007fe`e5735361 55 push rbp
000007fe`e5735362 56 push rsi
000007fe`e5735363 57 push rdi
000007fe`e5735364 4154 push r12
000007fe`e5735366 4883ec30 sub rsp,30h
000007fe`e573536a 498bf8 mov rdi,r8
000007fe`e573536d 8bea mov ebp,edx
000007fe`e573536f 48c744242800000000 mov qword ptr [rsp+28h],0
000007fe`e5735378 488bb42480000000 mov rsi,qword ptr [rsp+80h]
000007fe`e5735380 4889742420 mov qword ptr [rsp+20h],rsi
000007fe`e5735385 41b903000000 mov r9d,3
...
mscorlib_ni!System.RuntimeType.GetConstructorImpl(System.Reflection.BindingFlags, System.Reflection.Binder, System.Reflection.CallingConventions, System.Type[], System.Reflection.ParameterModifier[])+0x97:
000007fe`e57353f7 488b4b08 mov rcx,qword ptr [rbx+8]
000007fe`e57353fb 85c9 test ecx,ecx
000007fe`e57353fd 0f848e000000 je mscorlib_ni!System.RuntimeType.GetConstructorImpl(System.Reflection.BindingFlags, System.Reflection.Binder, System.Reflection.CallingConventions, System.Type[], System.Reflection.ParameterModifier[])+0x131 (000007fe`e5735491)
mscorlib_ni!System.RuntimeType.GetConstructorImpl(System.Reflection.BindingFlags, System.Reflection.Binder, System.Reflection.CallingConventions, System.Type[], System.Reflection.ParameterModifier[])+0xa3:
000007fe`e5735403 488b4608 mov rax,qword ptr [rsi+8]
000007fe`e5735407 85c0 test eax,eax
000007fe`e5735409 7545 jne mscorlib_ni!System.RuntimeType.GetConstructorImpl(System.Reflection.BindingFlags, System.Reflection.Binder, System.Reflection.CallingConventions, System.Type[], System.Reflection.ParameterModifier[])+0xf0 (000007fe`e5735450)
...
@rsi
从头开始加载,[rsp+20h]
因此必须由调用方传递。让我们看一下呼叫者:
0:000> k3
Child-SP RetAddr Call Site
00000000`001fec70 000007fe`8d450110 mscorlib_ni!System.RuntimeType.GetConstructorImpl(System.Reflection.BindingFlags, System.Reflection.Binder, System.Reflection.CallingConventions, System.Type[], System.Reflection.ParameterModifier[])+0xa3
00000000`001fecd0 000007fe`ecb6e073 image00000000_01120000!Test.Main()+0x60
00000000`001fed20 000007fe`ecb6dcb2 clr!CoUninitializeEE+0x7ae1f
0:000> ln 000007fe`8d450110
(000007fe`8d4500b0) image00000000_01120000!Test.Main()+0x60
0:000> uf 000007fe`8d4500b0
image00000000_01120000!Test.Main():
000007fe`8d4500b0 53 push rbx
000007fe`8d4500b1 4883ec40 sub rsp,40h
000007fe`8d4500b5 e8a69ba658 call mscorlib_ni!System.Console.get_In() (000007fe`e5eb9c60)
000007fe`8d4500ba 4c8bd8 mov r11,rax
000007fe`8d4500bd 498b03 mov rax,qword ptr [r11]
000007fe`8d4500c0 488b5048 mov rdx,qword ptr [rax+48h]
000007fe`8d4500c4 498bcb mov rcx,r11
000007fe`8d4500c7 ff5238 call qword ptr [rdx+38h]
000007fe`8d4500ca 488d0d7737eeff lea rcx,[000007fe`8d333848]
000007fe`8d4500d1 e88acb715f call clr!CoUninitializeEE+0x79a0c (000007fe`ecb6cc60)
000007fe`8d4500d6 4c8bd8 mov r11,rax
000007fe`8d4500d9 48b92012531200000000 mov rcx,12531220h
000007fe`8d4500e3 488b09 mov rcx,qword ptr [rcx]
000007fe`8d4500e6 498b03 mov rax,qword ptr [r11]
000007fe`8d4500e9 4c8b5068 mov r10,qword ptr [rax+68h]
000007fe`8d4500ed 48c744242800000000 mov qword ptr [rsp+28h],0
000007fe`8d4500f6 48894c2420 mov qword ptr [rsp+20h],rcx
000007fe`8d4500fb 41b903000000 mov r9d,3
000007fe`8d450101 4533c0 xor r8d,r8d
000007fe`8d450104 ba38000000 mov edx,38h
000007fe`8d450109 498bcb mov rcx,r11
000007fe`8d45010c 41ff5228 call qword ptr [r10+28h]
000007fe`8d450110 48bb1032531200000000 mov rbx,12533210h
000007fe`8d45011a 488b1b mov rbx,qword ptr [rbx]
000007fe`8d45011d 33d2 xor edx,edx
000007fe`8d45011f 488bc8 mov rcx,rax
000007fe`8d450122 e829452e58 call mscorlib_ni!System.Reflection.ConstructorInfo.op_Equality(System.Reflection.ConstructorInfo, System.Reflection.ConstructorInfo) (000007fe`e5734650)
000007fe`8d450127 0fb6c8 movzx ecx,al
000007fe`8d45012a 33c0 xor eax,eax
000007fe`8d45012c 85c9 test ecx,ecx
000007fe`8d45012e 0f94c0 sete al
000007fe`8d450131 0fb6c8 movzx ecx,al
000007fe`8d450134 894c2430 mov dword ptr [rsp+30h],ecx
000007fe`8d450138 488d542430 lea rdx,[rsp+30h]
000007fe`8d45013d 488d0d24224958 lea rcx,[mscorlib_ni+0x682368 (000007fe`e58e2368)]
000007fe`8d450144 e807246a5f call clr+0x2550 (000007fe`ecaf2550)
000007fe`8d450149 488bd0 mov rdx,rax
000007fe`8d45014c 488bcb mov rcx,rbx
000007fe`8d45014f e81cab2758 call mscorlib_ni!System.Console.WriteLine(System.String, System.Object) (000007fe`e56cac70)
000007fe`8d450154 90 nop
000007fe`8d450155 4883c440 add rsp,40h
000007fe`8d450159 5b pop rbx
000007fe`8d45015a c3 ret
(我的反汇编显示是System.Console.get_In
因为我Console.GetLine()
在test.cs中添加了一个有机会闯入调试器的机会。我验证了它不会改变行为)。
我们正在进行此调用:(000007fe8d45010c 41ff5228 call qword ptr [r10+28h]
我们的AV帧ret地址是紧随其后的指令call
)。
让我们将其与编译时发生的情况进行比较csc /debug test.cs
。我们可以设置一个bp 000007fee5735360
,幸运的是模块加载到相同的地址。在加载的指令上@rsi
:
0:000> r
rax=000007fee58e2f30 rbx=00000000027c6258 rcx=00000000027c6258
rdx=0000000000000038 rsi=00000000002debd8 rdi=0000000000000000
rip=000007fee5735378 rsp=00000000002de990 rbp=0000000000000038
r8=0000000000000000 r9=0000000000000003 r10=000007fee58831c8
r11=00000000002de9c0 r12=0000000000000000 r13=00000000002dedc0
r14=00000000002dec58 r15=0000000000000004
iopl=0 nv up ei pl nz na po nc
cs=0033 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000206
mscorlib_ni!System.RuntimeType.GetConstructorImpl(System.Reflection.BindingFlags, System.Reflection.Binder, System.Reflection.CallingConventions, System.Type[], System.Reflection.ParameterModifier[])+0x18:
000007fe`e5735378 488bb42480000000 mov rsi,qword ptr [rsp+80h] ss:00000000`002dea10=a0627c0200000000
请注意@rsi
是00000000002debd8。单步执行该功能将显示此地址,该地址稍后将在坏exe炸弹(即@rsi
不变)时被取消引用。堆栈非常有趣,因为它显示了一个额外的帧:
0:000> k3
Child-SP RetAddr Call Site
00000000`002de990 000007fe`e5eddf68 mscorlib_ni!System.RuntimeType.GetConstructorImpl(System.Reflection.BindingFlags, System.Reflection.Binder, System.Reflection.CallingConventions, System.Type[], System.Reflection.ParameterModifier[])+0x18
00000000`002de9f0 000007fe`8d460119 mscorlib_ni!System.Type.get_TypeInitializer()+0x48
00000000`002dea30 000007fe`ecb6e073 good!Test.Main()+0x49*** WARNING: Unable to verify checksum for good.exe
0:000> ln 000007fe`e5eddf68
(000007fe`e5eddf20) mscorlib_ni!System.Type.get_TypeInitializer()+0x48
0:000> uf 000007fe`e5eddf20
mscorlib_ni!System.Type.get_TypeInitializer():
000007fe`e5eddf20 53 push rbx
000007fe`e5eddf21 4883ec30 sub rsp,30h
000007fe`e5eddf25 488bd9 mov rbx,rcx
000007fe`e5eddf28 ba22010000 mov edx,122h
000007fe`e5eddf2d b901000000 mov ecx,1
000007fe`e5eddf32 e8d1a075ff call CORINFO_HELP_GETSHARED_GCSTATIC_BASE (000007fe`e5638008)
000007fe`e5eddf37 488b88f0010000 mov rcx,qword ptr [rax+1F0h]
000007fe`e5eddf3e 488b03 mov rax,qword ptr [rbx]
000007fe`e5eddf41 4c8b5068 mov r10,qword ptr [rax+68h]
000007fe`e5eddf45 48c744242800000000 mov qword ptr [rsp+28h],0
000007fe`e5eddf4e 48894c2420 mov qword ptr [rsp+20h],rcx
000007fe`e5eddf53 41b903000000 mov r9d,3
000007fe`e5eddf59 4533c0 xor r8d,r8d
000007fe`e5eddf5c ba38000000 mov edx,38h
000007fe`e5eddf61 488bcb mov rcx,rbx
000007fe`e5eddf64 41ff5228 call qword ptr [r10+28h]
000007fe`e5eddf68 90 nop
000007fe`e5eddf69 4883c430 add rsp,30h
000007fe`e5eddf6d 5b pop rbx
000007fe`e5eddf6e c3 ret
0:000> ln 000007fe`8d460119
调用与call qword ptr [r10+28h]
我们之前看到的相同,因此在坏情况下,此函数可能内联了Main()
,因此存在多余的帧的事实是红色鲱鱼。如果我们看一下它的准备工作,call qword ptr [r10+28h]
则会注意到以下说明:mov qword ptr [rsp+20h],rcx
。这就是加载最终被取消引用为的地址的原因@rsi
。在好的情况下,这是如何@rcx
加载的:
000007fe`e5eddf32 e8d1a075ff call CORINFO_HELP_GETSHARED_GCSTATIC_BASE (000007fe`e5638008)
000007fe`e5eddf37 488b88f0010000 mov rcx,qword ptr [rax+1F0h]
在最坏的情况下,它看起来非常不同:
000007fe`8d4600d9 48b92012721200000000 mov rcx,12721220h
000007fe`8d4600e3 488b09 mov rcx,qword ptr [rcx]
这是非常不同的。与调用CORINFO_HELP_GETSHARED_GCSTATIC_BASE并读取最终结果的关键情况不同,该关键情况导致从某个成员1F0
返回的AV 在返回结构中偏移,优化的代码从静态地址加载它。并且当然12721220h包含NULL:
0:000> dp 12721220h L8
00000000`12721220 00000000`00000000 00000000`00000000
00000000`12721230 00000000`00000000 00000000`02722198
00000000`12721240 00000000`027221c8 00000000`027221f8
00000000`12721250 00000000`02722228 00000000`02722258
不幸的是,现在对我进行更深入的研究已经为时已晚,其缺点CORINFO_HELP_GETSHARED_GCSTATIC_BASE
远非琐碎。我发布此消息的目的是希望对CLR内部知识更了解的人可以理解(如您所见,我真的只是从本机指令POV考虑了这个问题,而完全忽略了IL)。