[llvm] [llvm-objdump][ELF]Fix crash when reading strings from .dynstr(#86612) (PR #125679)

[James Henderson via llvm-commits]

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@@ -221,6 +224,20 @@ template <class ELFT> void ELFDumper<ELFT>::printDynamicSection() {
   std::string TagFmt = "  %-" + std::to_string(MaxLen) + "s ";
 
   outs() << "\nDynamic Section:\n";
+  auto StringTableSize = (typename ELFT::Xword)0;
+  for (const auto &Sec : cantFail(Elf.sections())) {
+    if (Sec.sh_type == ELF::SHT_STRTAB)
+      StringTableSize =
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jh7370 wrote:

1) If I'm not mistaken, this assignment could easily pick up the wrong string table section, e.g. the .strtab section containing symbol and section names, and not the dynamic string table, rendering the subsequent usage incorrect.
2) I don't follow what the point of the subsequent ternary is; presumably it's related to point 1 above.

I think you need to look for the dynamic string table referenced by the dynamic section (it's the section with index matching the sh_link field of the dynamic section).

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