Meinersbur added inline comments.
================
Comment at: clang/lib/Parse/ParsePragma.cpp:1010
+ StringRef Str = PragmaName.getIdentifierInfo()->getName();
+ StringRef ClangLoopStr = "clang loop " + Str.str();
+ Str = llvm::StringSwitch<StringRef>(Str)
----------------
[serious] Use-after-free here again. This line will do the following:
```
StringRef ClangLoopStr;
{
std::string tmp = "clang loop " + Str.str()
ClangLoopStr = tmp;
// tmp.~string()
}
// Any use of ClangLoopStr will use memory released by tmp.~string()
```
Let me suggest a solution:
```
std::string ClangLoopStr = (Twine("clang loop ") + Str).str();
std::string Result = llvm::StringSwitch<StringRef>(Str)
.Case("loop", ClangLoopStr)
.Case("unroll_and_jam", Str)
.Case("unroll", Str)
.Default("");
return Result; // NRVO, ClangLoopStr will be released here, but if it was
chosen by the StringSwitch, Result will hold a copy, so ClangLoopStr is not
referenced anymore.
```
Note that this will alloc one more std::string in the non-ClangLoopStr cases
than before the patch, but I don't think it's important.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D64564/new/
https://reviews.llvm.org/D64564
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