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

[James Henderson via llvm-commits]

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@@ -63,14 +63,22 @@ static Expected<StringRef> getDynamicStrTab(const ELFFile<ELFT> &Elf) {
   if (!DynamicEntriesOrError)
     return DynamicEntriesOrError.takeError();
 
+  typename ELFT::Xword StringTableSize{0};
+  const uint8_t *MappedAddr = nullptr;
   for (const typename ELFT::Dyn &Dyn : *DynamicEntriesOrError) {
     if (Dyn.d_tag == ELF::DT_STRTAB) {
       auto MappedAddrOrError = Elf.toMappedAddr(Dyn.getPtr());
       if (!MappedAddrOrError)
         return MappedAddrOrError.takeError();
-      return StringRef(reinterpret_cast<const char *>(*MappedAddrOrError));
+      MappedAddr = *MappedAddrOrError;
+    }
+    if (Dyn.d_tag == ELF::DT_STRSZ) {
+      StringTableSize = Dyn.getVal();
     }
   }
+  if (MappedAddr && StringTableSize)
+    return StringRef(reinterpret_cast<const char *>(MappedAddr),
+                     StringTableSize);
 
   // If the dynamic segment is not present, we fall back on the sections.
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jh7370 wrote:

Update this comment to mention that if it "is not present, or is missing the important tags, ...".

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