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[win/asan] Don't intercept memset etc. in ntdll #120397

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Merged
merged 2 commits into from
Dec 20, 2024
Merged

[win/asan] Don't intercept memset etc. in ntdll #120397

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91b49f1
[win/asan] Don't intercept memset etc. in ntdll
zmodem Dec 17, 2024
8959e64
use an internal strcmp
zmodem Dec 19, 2024
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16 changes: 14 additions & 2 deletions compiler-rt/lib/interception/interception_win.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1177,8 +1177,7 @@ static void **InterestingDLLsAvailable() {
"libc++.dll", // libc++
"libunwind.dll", // libunwind
# endif
// NTDLL should go last as it exports some functions that we should
// override in the CRT [presumably only used internally].
// NTDLL must go last as it gets special treatment in OverrideFunction.
"ntdll.dll",
NULL
};
Expand Down Expand Up @@ -1281,9 +1280,22 @@ uptr InternalGetProcAddress(void *module, const char *func_name) {

bool OverrideFunction(
const char *func_name, uptr new_func, uptr *orig_old_func) {
static const char *kNtDllIgnore[] = {
"memcmp", "memcpy", "memmove", "memset"
};

bool hooked = false;
void **DLLs = InterestingDLLsAvailable();
for (size_t i = 0; DLLs[i]; ++i) {
if (DLLs[i + 1] == nullptr) {
// This is the last DLL, i.e. NTDLL. It exports some functions that
// we only want to override in the CRT.
for (const char *ignored : kNtDllIgnore) {
if (strcmp(func_name, ignored) == 0)
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Is there some internal_strcmp function we should be calling instead in order to avoid libc re-entrancy, like hitting the ASan strcmp interceptor, for example?

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Done.

return hooked;
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Nit, let's just break or continue so the reader doesn't have to think about what hooked is, we just hit the shared return codepath.

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It's a nested loop, I think returning is the most straight-forward.

}
}

uptr func_addr = InternalGetProcAddress(DLLs[i], func_name);
if (func_addr &&
OverrideFunction(func_addr, new_func, orig_old_func)) {
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