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

[Ruoyu Qiu 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 =
+          StringTableSize < Sec.sh_size ? Sec.sh_size : StringTableSize;
+  }
+  for (const typename ELFT::Dyn &Dyn : DynamicEntries) {
+    if (Dyn.d_tag == ELF::DT_STRSZ) {
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cabbaken wrote:

I check `SHT_STRTAB` because, in `getDynamicStrTab(Elf)`, I noticed that both dynamic entries and sections are checked. Therefore, I believe checking the sections is necessary.
The test(`tools/llvm-objdump/ELF/private-headers.test`) will fail without this check.

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