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[win/asan] GetInstructionSize: Detect 66 90 two-byte NOP at 32-bit too. (#132267)

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Observed in Wine when trying to intercept `ExitThread`, which forwards
to `ntdll.RtlExitUserThread`.

`gdb` interprets it as `xchg %ax,%ax`.
`llvm-mc` outputs simply `nop`.

```
==Asan-i386-calls-Dynamic-Test.exe==964==interception_win: unhandled instruction at 0x7be27cf0: 66 90 55 89 e5 56 50 8b
```

```
Wine-gdb> bt
#0  0x789a1766 in __interception::GetInstructionSize (address=<optimized out>, rel_offset=<optimized out>) at C:/llvm-mingw/llvm-mingw/llvm-project/compiler-rt/lib/interception/interception_win.cpp:983
#1  0x789ab480 in __sanitizer::SharedPrintfCode(bool, char const*, char*) () at C:/llvm-mingw/llvm-mingw/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_printf.cpp:311
#2  0x789a18e7 in __interception::OverrideFunctionWithHotPatch (old_func=2078440688, new_func=2023702608, orig_old_func=warning: (Internal error: pc 0x792f1a2c in read in CU, but not in symtab.)warning: (Error: pc 0x792f1a2c in address map, but not in symtab.)0x792f1a2c) at C:/llvm-mingw/llvm-mingw/llvm-project/compiler-rt/lib/interception/interception_win.cpp:1118
#3  0x789a1f34 in __interception::OverrideFunction (old_func=2078440688, new_func=2023702608, orig_old_func=warning: (Internal error: pc 0x792f1a2c in read in CU, but not in symtab.)warning: (Error: pc 0x792f1a2c in address map, but not in symtab.)0x792f1a2c) at C:/llvm-mingw/llvm-mingw/llvm-project/compiler-rt/lib/interception/interception_win.cpp:1224
#4  0x789a24ce in __interception::OverrideFunction (func_name=0x78a0bc43 <vtable for __asan::AsanThreadContext+1163> "ExitThread", new_func=2023702608, orig_old_func=warning: (Internal error: pc 0x792f1a2c in read in CU, but not in symtab.)warning: (Error: pc 0x792f1a2c in address map, but not in symtab.)0x792f1a2c)    at C:/llvm-mingw/llvm-mingw/llvm-project/compiler-rt/lib/interception/interception_win.cpp:1369
#5  0x789f40ef in __asan::InitializePlatformInterceptors () at C:/llvm-mingw/llvm-mingw/llvm-project/compiler-rt/lib/asan/asan_win.cpp:190
#6  0x789e0c3c in __asan::InitializeAsanInterceptors () at C:/llvm-mingw/llvm-mingw/llvm-project/compiler-rt/lib/asan/asan_interceptors.cpp:802
#7  0x789ee6b5 in __asan::AsanInitInternal () at C:/llvm-mingw/llvm-mingw/llvm-project/compiler-rt/lib/asan/asan_rtl.cpp:442
#8  0x789eefb0 in __asan::AsanInitFromRtl () at C:/llvm-mingw/llvm-mingw/llvm-project/compiler-rt/lib/asan/asan_rtl.cpp:522
#9  __asan::AsanInitializer::AsanInitializer (this=<optimized out>) at C:/llvm-mingw/llvm-mingw/llvm-project/compiler-rt/lib/asan/asan_rtl.cpp:542
#10 __cxx_global_var_init () at C:/llvm-mingw/llvm-mingw/llvm-project/compiler-rt/lib/asan/asan_rtl.cpp:546
...
Wine-gdb> disassemble /r 2078440688,2078440688+20
Dump of assembler code from 0x7be27cf0 to 0x7be27d04:
   0x7be27cf0 <_RtlExitUserThread@4+0>: 66 90                   xchg   %ax,%ax
...
```
This commit is contained in:
bernhardu 2025-03-21 14:45:20 +01:00 committed by GitHub
parent af93db9344
commit 610ade2ed7
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GPG Key ID: B5690EEEBB952194
2 changed files with 2 additions and 2 deletions
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2
compiler-rt/lib/interception/interception_win.cpp
View File

@ -646,6 +646,7 @@ static size_t GetInstructionSize(uptr address, size_t* rel_offset = nullptr) {
case 0xC033: // 33 C0 : xor eax, eax
case 0xC933: // 33 C9 : xor ecx, ecx
case 0xD233: // 33 D2 : xor edx, edx
case 0x9066: // 66 90 : xchg %ax,%ax (Two-byte NOP)
case 0xDB84: // 84 DB : test bl,bl
case 0xC084: // 84 C0 : test al,al
case 0xC984: // 84 C9 : test cl,cl
@ -726,7 +727,6 @@ static size_t GetInstructionSize(uptr address, size_t* rel_offset = nullptr) {
case 0x5541: // push r13
case 0x5641: // push r14
case 0x5741: // push r15
case 0x9066: // Two-byte NOP
case 0xc084: // test al, al
case 0x018a: // mov al, byte ptr [rcx]
return 2;

2
compiler-rt/lib/interception/tests/interception_win_test.cpp
View File

@ -845,6 +845,7 @@ const struct InstructionSizeData {
{ 2, {0x33, 0xC0}, 0, "33 C0 : xor eax, eax"},
{ 2, {0x33, 0xC9}, 0, "33 C9 : xor ecx, ecx"},
{ 2, {0x33, 0xD2}, 0, "33 D2 : xor edx, edx"},
{ 2, {0x66, 0x90}, 0, "66 90 : xchg %ax,%ax (Two-byte NOP)"},
{ 2, {0x6A, 0x71}, 0, "6A XX : push XX"},
{ 2, {0x84, 0xC0}, 0, "84 C0 : test al,al"},
{ 2, {0x84, 0xC9}, 0, "84 C9 : test cl,cl"},
@ -887,7 +888,6 @@ const struct InstructionSizeData {
{ 2, {0x41, 0x55}, 0, "41 55 : push r13"},
{ 2, {0x41, 0x56}, 0, "41 56 : push r14"},
{ 2, {0x41, 0x57}, 0, "41 57 : push r15"},
{ 2, {0x66, 0x90}, 0, "66 90 : Two-byte NOP"},
{ 2, {0x84, 0xc0}, 0, "84 c0 : test al, al"},
{ 2, {0x8a, 0x01}, 0, "8a 01 : mov al, byte ptr [rcx]"},
{ 3, {0x0f, 0xb6, 0x01}, 0, "0f b6 01 : movzx eax, BYTE PTR [rcx]"},