[PATCH] [Request, 7 lines] D25087: [Object/ELF] - Do check for invalid section header entry size earlier.

[George Rimar via llvm-commits]

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

Zero value in e_shentsize was the reason of crash in lld.
When we have zero size and huge amount of sections,
resize() in below code could fail.

  template <class ELFT>
  void elf::ObjectFile<ELFT>::initializeSections(
      DenseSet<StringRef> &ComdatGroups) {
    uint64_t Size = this->ELFObj.getNumSections();
    Sections.resize(Size);

No any new testcase as this fatal message is already has one.


https://reviews.llvm.org/D25087

Files:
  ELF.h


Index: ELF.h
===================================================================
--- ELF.h
+++ ELF.h
@@ -356,6 +356,10 @@
     return;
   }
 
+  if (Header->e_shentsize != sizeof(Elf_Shdr))
+    report_fatal_error(
+        "Invalid section header entry size (e_shentsize) in ELF header");
+
   // The getNumSections() call below depends on SectionHeaderTable being set.
   SectionHeaderTable =
     reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
@@ -390,9 +394,6 @@
 
 template <class ELFT>
 const typename ELFFile<ELFT>::Elf_Shdr *ELFFile<ELFT>::section_begin() const {
-  if (Header->e_shentsize != sizeof(Elf_Shdr))
-    report_fatal_error(
-        "Invalid section header entry size (e_shentsize) in ELF header");
   return reinterpret_cast<const Elf_Shdr *>(base() + Header->e_shoff);
 }
 


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