[llvm-objdump][ELF] Add Section size check. (#86612)

This change make the check of the section size to
avoid crashing of llvm-objdump when processing
misformated elf file.

Signed-off-by: cabbaken <[email protected]>

Author: cabbaken

llvm/tools/llvm-objdump/ELFDump.cpp

@@ -221,6 +221,13 @@ template <class ELFT> void ELFDumper<ELFT>::printDynamicSection() {
   std::string TagFmt = "  %-" + std::to_string(MaxLen) + "s ";
 
   outs() << "\nDynamic Section:\n";
+  auto DynamicSectionOrErr = Elf.getSection(ELF::SHT_DYNAMIC);
+  if (!DynamicSectionOrErr) {
+    reportWarning(toString(DynamicSectionOrErr.takeError()), Obj.getFileName());
+    return;
+  }
+  const auto StringTableSize = (*DynamicSectionOrErr)->sh_size;
+
   for (const typename ELFT::Dyn &Dyn : DynamicEntries) {
     if (Dyn.d_tag == ELF::DT_NULL)
       continue;
@@ -235,6 +242,11 @@ 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 for section .dynstr",
+                        Obj.getFileName());
+          continue;
+        }
         outs() << format(TagFmt.c_str(), Str.c_str()) << Data + Dyn.getVal()
                << "\n";
         continue;