[ELF] - Do not crash on invalid size of dynamic section.

[grimar]

Summary

Previously if sh_size of dynamic section was broken,
lld may crash. Or even may not crash if used 32 bits host.
(then value may be truncated to 32 bits when doing pointer arithmetic
and could be just zero).
Patch fixes the issue.

[ruiu]

LGTM

ELF/InputFiles.cpp

524 ↗

(On Diff #73797)

getFilename(this) + ": getSectionContentsAsArray failed"

lld/trunk/ELF/InputFiles.cpp

template <class ELFT> void SharedFile<ELFT>::parseSoName() {
 
   // DSOs are identified by soname, and they usually contain
   // DT_SONAME tag in their header. But if they are missing,
   // filenames are used as default sonames.
   SoName = sys::path::filename(this->getName());
 
   if (!DynamicSec)
     return;
-  auto *Begin =
-      reinterpret_cast<const Elf_Dyn *>(Obj.base() + DynamicSec->sh_offset);
-  const Elf_Dyn *End = Begin + DynamicSec->sh_size / sizeof(Elf_Dyn);
 
-  for (const Elf_Dyn &Dyn : make_range(Begin, End)) {
+  ArrayRef<Elf_Dyn> Arr =
+      check(Obj.template getSectionContentsAsArray<Elf_Dyn>(DynamicSec),
+            getFilename(this) + ": getSectionContentsAsArray failed");
+  for (const Elf_Dyn &Dyn : Arr) {
     if (Dyn.d_tag == DT_SONAME) {
       uintX_t Val = Dyn.getVal();
       if (Val >= this->StringTable.size())
         fatal(getFilename(this) + ": invalid DT_SONAME entry");
       SoName = StringRef(this->StringTable.data() + Val);
       return;
     }
   }

lld/trunk/test/ELF/invalid/dynamic-section-size.s

+## dynamic-section-sh_size.elf has incorrect sh_size of dynamic section.
+# RUN: not ld.lld %p/Inputs/dynamic-section-sh_size.elf -o %t2 2>&1 | \
+# RUN:   FileCheck %s
+# CHECK: getSectionContentsAsArray failed: Invalid data was encountered while parsing the file