Revert "[Object/ELF.h] - Improve testing of the fields in ELFFile<ELFT>::sections()."

This reverts commit r366796 because it was causing ubsan buildbot
failures.

llvm-svn: 366815

llvm/include/llvm/Object/ELF.h

@@ -513,22 +513,15 @@ Expected<typename ELFT::ShdrRange> ELFFile<ELFT>::sections() const {
     NumSections = First->sh_size;
 
   if (NumSections > UINT64_MAX / sizeof(Elf_Shdr))
-    return createError("invalid number of sections specified in the NULL "
-                       "section's sh_size field (" +
-                       Twine(NumSections) + ")");
+    // TODO: this error is untested.
+    return createError("section table goes past the end of file");
 
   const uint64_t SectionTableSize = NumSections * sizeof(Elf_Shdr);
-  if (SectionTableOffset + SectionTableSize < SectionTableOffset)
-    return createError(
-        "invalid section header table offset (e_shoff = 0x" +
-        Twine::utohexstr(SectionTableOffset) +
-        ") or invalid number of sections specified in the first section "
-        "header's sh_size field (0x" +
-        Twine::utohexstr(NumSections) + ")");
 
   // Section table goes past end of file!
   if (SectionTableOffset + SectionTableSize > FileSize)
     return createError("section table goes past the end of file");
+
   return makeArrayRef(First, NumSections);
 }
 

llvm/include/llvm/ObjectYAML/ELFYAML.h

@@ -77,7 +77,7 @@ struct FileHeader {
   llvm::yaml::Hex64 Entry;
 
   Optional<llvm::yaml::Hex16> SHEntSize;
-  Optional<llvm::yaml::Hex64> SHOffset;
+  Optional<llvm::yaml::Hex16> SHOffset;
   Optional<llvm::yaml::Hex16> SHNum;
   Optional<llvm::yaml::Hex16> SHStrNdx;
 };

llvm/test/Object/invalid.test

@@ -552,58 +552,3 @@ FileHeader:
 Sections:
   - Name: .foo
     Type: SHT_PROGBITS
-
-## We report an error if the number of sections stored in sh_size
-## is greater than UINT64_MAX / sizeof(Elf_Shdr) == 288230376151711743.
-## Here we check that do not crash on a border value.
-
-# RUN: yaml2obj --docnum=26 %s -o %t26
-# RUN: not llvm-readobj -h %t26 2>&1 | FileCheck -DFILE=%t26 --check-prefix=INVALID-SEC-NUM1 %s
-
-# INVALID-SEC-NUM1: error: '[[FILE]]': invalid section header table offset (e_shoff = 0x40) or invalid number of sections specified in the first section header's sh_size field (0x3ffffffffffffff)
-
---- !ELF
-FileHeader:
-  Class:   ELFCLASS64
-  Data:    ELFDATA2LSB
-  Type:    ET_REL
-  Machine: EM_X86_64
-  SHNum:   0x0
-Sections:
-  - Type: SHT_NULL
-    Size: 288230376151711743
-
-## See above, but now we test the UINT64_MAX / sizeof(Elf_Shdr) value.
-## The error is slightly different in this case.
-
-# RUN: yaml2obj --docnum=27 %s -o %t27
-# RUN: not llvm-readobj -h %t27 2>&1 | FileCheck -DFILE=%t27 --check-prefix=INVALID-SEC-NUM2 %s
-
-# INVALID-SEC-NUM2: error: '[[FILE]]': invalid number of sections specified in the NULL section's sh_size field (288230376151711744)
-
---- !ELF
-FileHeader:
-  Class:   ELFCLASS64
-  Data:    ELFDATA2LSB
-  Type:    ET_REL
-  Machine: EM_X86_64
-  SHNum:   0x0
-Sections:
-  - Type: SHT_NULL
-    Size: 288230376151711744
-
-## Check the case when SHOffset is too large, but SHNum is not. SHOffset + SHNum overflows the uint64 type.
-
-# RUN: yaml2obj --docnum=28 %s -o %t28
-# RUN: not llvm-readobj -h %t28 2>&1 | FileCheck -DFILE=%t28 --check-prefix=INVALID-SEC-NUM3 %s
-
-# INVALID-SEC-NUM3: error: '[[FILE]]': invalid section header table offset (e_shoff = 0xffffffffffffffff) or invalid number of sections specified in the first section header's sh_size field (0x1)
-
---- !ELF
-FileHeader:
-  Class:    ELFCLASS64
-  Data:     ELFDATA2LSB
-  Type:     ET_REL
-  Machine:  EM_X86_64
-  SHOffset: 0xffffffffffffffff
-  SHNum:    0x1

llvm/tools/yaml2obj/yaml2elf.cpp

@@ -244,7 +244,7 @@ void ELFState<ELFT>::initELFHeader(Elf_Ehdr &Header) {
   // Immediately following the ELF header and program headers.
   Header.e_shoff =
       Doc.Header.SHOffset
-          ? (typename ELFT::uint)(*Doc.Header.SHOffset)
+          ? (uint16_t)*Doc.Header.SHOffset
           : sizeof(Header) + sizeof(Elf_Phdr) * Doc.ProgramHeaders.size();
   Header.e_shnum =
       Doc.Header.SHNum ? (uint16_t)*Doc.Header.SHNum : SN2I.size() + 1;