[ELF] - Do not crash if common symbol alignment set to value greater than UINT32_MAX.

[grimar]

Summary

We have following code in lld, that truncates the alignment value to 32 bit. Big alignment in this case
may give result 0 and crash later.

template <class ELFT>
CommonInputSection<ELFT>::CommonInputSection(std::vector<DefinedCommon *> Syms)
    : InputSection<ELFT>(nullptr, &Hdr, "") {
....
  for (DefinedCommon *Sym : Syms) {
    this->Alignment = std::max<uintX_t>(this->Alignment, Sym->Alignment);
...
  }
}

Patch fixes the issue. I did not find the way to generate object using yaml2obj for that case.

[• rafael]

LGTM

[ruiu]

ELF/InputFiles.cpp

405

"': invalid alignment: " + Twine(Sym->st_value

is probably more helpful.

[grimar]

Revision: 283738

ELF/InputFiles.cpp

SymbolBody *elf::ObjectFile<ELFT>::createSymbolBody(const Elf_Sym *Sym) {
 
   switch (Sym->st_shndx) {
   case SHN_UNDEF:
     return elf::Symtab<ELFT>::X->addUndefined(Name, Binding, Sym->st_other,
                                               Sym->getType(),
                                               /*CanOmitFromDynSym*/ false, this)
         ->body();
   case SHN_COMMON:
-    if (Sym->st_value == 0)
+    if (Sym->st_value == 0 || Sym->st_value >= UINT32_MAX)
       fatal(getFilename(this) + ": common symbol '" + Name +
-            "' alignment is 0");
+            "' alignment is 0 or too large");
     return elf::Symtab<ELFT>::X->addCommon(Name, Sym->st_size, Sym->st_value,
                                            Binding, Sym->st_other,
                                            Sym->getType(), this)
         ->body();
   }
 
   switch (Binding) {
   default:

test/ELF/invalid/common-symbol-alignment.s

 # REQUIRES: x86
 
 ## common-symbol-alignment.elf contains common symbol with zero alignment.
 # RUN: not ld.lld %S/Inputs/common-symbol-alignment.elf \
 # RUN:   -o %t 2>&1 | FileCheck %s
-# CHECK: common symbol 'bar' alignment is 0
+# CHECK: common symbol 'bar' alignment is 0 or too large
+
+## common-symbol-alignment2.elf contains common symbol alignment greater
+## than UINT32_MAX.
+# RUN: not ld.lld %S/Inputs/common-symbol-alignment2.elf \
+# RUN:   -o %t 2>&1 | FileCheck %s