[PATCH] D25235: [ELF] - Do not crash if common symbol alignment set to value greater than UINT32_MAX.

[George Rimar via llvm-commits]

grimar created this revision.
grimar added reviewers: ruiu, rafael, davide.
grimar added subscribers: llvm-commits, grimar, evgeny777.

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.


https://reviews.llvm.org/D25235

Files:
  ELF/InputFiles.cpp
  test/ELF/invalid/Inputs/common-symbol-alignment2.elf
  test/ELF/invalid/common-symbol-alignment.s


Index: test/ELF/invalid/common-symbol-alignment.s
===================================================================
--- test/ELF/invalid/common-symbol-alignment.s
+++ test/ELF/invalid/common-symbol-alignment.s
@@ -3,4 +3,9 @@
 ## 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
Index: ELF/InputFiles.cpp
===================================================================
--- ELF/InputFiles.cpp
+++ ELF/InputFiles.cpp
@@ -400,9 +400,9 @@
                                               /*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)


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