[llvm] [llvm-objdump][ELF]Fix crash when reading strings from .dynstr (PR #125679)

[James Henderson via llvm-commits]

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@@ -235,6 +252,12 @@ template <class ELFT> void ELFDumper<ELFT>::printDynamicSection() {
       Expected<StringRef> StrTabOrErr = getDynamicStrTab(Elf);
       if (StrTabOrErr) {
         const char *Data = StrTabOrErr->data();
+        if (Dyn.getVal() >= StringTableSize) {
+          reportWarning("invalid string table offset", Obj.getFileName());
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jh7370 wrote:

`std::format` is C++20 and LLVM currently uses C++17, so that's not an option. There are various options, but LLVM already has plenty of good mechanisms for formatting things. In particular, the `Twine` class can be used to convert a number to a string and provides efficient concatenation with other `Twine` instances. There are also functions like `utohexstr` to make a `Twine` that is the hex form of a value, if you want to use that. An example of putting this all together is something like https://github.com/llvm/llvm-project/blob/37f36cbffb890a0c144211dec0c3589bd17f2a36/llvm/tools/llvm-objdump/llvm-objdump.cpp#L1265.

https://github.com/llvm/llvm-project/pull/125679