[ELF] - Check that .dynsym is present in DSO if SHT_GNU_versym section is.

When we have SHT_GNU_versym section, it is should be associated with symbol table
section. Usually (and in out implementation) it is .dynsym.
In case when .dynsym is absent (due to broken object for example), 
lld crashes in parseVerdefs() when accesses null pointer:

Versym = reinterpret_cast<const Elf_Versym *>(this->ELFObj.base() +
                                              VersymSec->sh_offset) +
         this->Symtab->sh_info;

DIfferential revision: https://reviews.llvm.org/D25553

llvm-svn: 285796

3 files changed, 30 insertions, 1 deletions

diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index 6900f8f325d..25fff944c2e 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -610,6 +610,9 @@ template <class ELFT> void SharedFile<ELFT>::parseSoName() {
     }
   }
 
+  if (this->VersymSec && !this->Symtab)
+    error("SHT_GNU_versym should be associated with symbol table");
+
   this->initStringTable();
 
   // DSOs are identified by soname, and they usually contain
diff --git a/lld/ELF/SymbolTable.cpp b/lld/ELF/SymbolTable.cpp
index c45ab94d0b5..0d8c62dd475 100644
--- a/lld/ELF/SymbolTable.cpp
+++ b/lld/ELF/SymbolTable.cpp
@@ -77,7 +77,7 @@ template <class ELFT> void SymbolTable<ELFT>::addFile(InputFile *File) {
   if (auto *F = dyn_cast<SharedFile<ELFT>>(File)) {
     // DSOs are uniquified not by filename but by soname.
     F->parseSoName();
-    if (!SoNames.insert(F->getSoName()).second)
+    if (HasError || !SoNames.insert(F->getSoName()).second)
       return;
     SharedFiles.push_back(F);
     F->parseRest();
diff --git a/lld/test/ELF/invalid/verdef-no-symtab.test b/lld/test/ELF/invalid/verdef-no-symtab.test
new file mode 100644
index 00000000000..5b5c32e4ff5
--- /dev/null
+++ b/lld/test/ELF/invalid/verdef-no-symtab.test
@@ -0,0 +1,26 @@
+# RUN: yaml2obj %s -o %t
+# RUN: not ld.lld %t -o %tout 2>&1 | FileCheck %s
+
+## When we have SHT_GNU_versym section, it is should be associated
+## with symbol table section.
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_DYN
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .versym
+    Type:            SHT_GNU_versym
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x1
+    Content:         "00000000"
+
+  - Name:            .verdef
+    Type:            SHT_GNU_verdef
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x1
+    Content:         "00000000"
+
+
+# CHECK: SHT_GNU_versym should be associated with symbol table