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[llvm-readobj/libObject] - Allow dumping objects that has a broken SHT_SYMTAB_SHNDX section.

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Currently it is impossible to create an instance of ELFObjectFile when the
SHT_SYMTAB_SHNDX can't be read. We error out when fail to parse the
SHT_SYMTAB_SHNDX section in the factory method.

This change delays reading of the SHT_SYMTAB_SHNDX section entries,
with it llvm-readobj is now able to work with such inputs.

Differential revision: https://reviews.llvm.org/D89379
This commit is contained in:
Georgii Rymar 2020-10-13 16:17:04 +03:00
parent cf35e6aad4
commit d2ae6e2eba
8 changed files with 129 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
include/llvm/Object/ELFObjectFile.h
View File

@ -249,14 +249,14 @@ public:
private:
ELFObjectFile(MemoryBufferRef Object, ELFFile<ELFT> EF,
const Elf_Shdr *DotDynSymSec, const Elf_Shdr *DotSymtabSec,
ArrayRef<Elf_Word> ShndxTable);
const Elf_Shdr *DotSymtabShndxSec);
protected:
ELFFile<ELFT> EF;
const Elf_Shdr *DotDynSymSec = nullptr; // Dynamic symbol table section.
const Elf_Shdr *DotSymtabSec = nullptr; // Symbol table section.
ArrayRef<Elf_Word> ShndxTable;
const Elf_Shdr *DotSymtabShndxSec = nullptr; // SHT_SYMTAB_SHNDX section.
void moveSymbolNext(DataRefImpl &Symb) const override;
Expected<StringRef> getSymbolName(DataRefImpl Symb) const override;
@ -538,6 +538,16 @@ ELFObjectFile<ELFT>::getSymbolAddress(DataRefImpl Symb) const {
return SymTabOrErr.takeError();
if (EF.getHeader().e_type == ELF::ET_REL) {
ArrayRef<Elf_Word> ShndxTable;
if (DotSymtabShndxSec) {
// TODO: Test this error.
if (Expected<ArrayRef<Elf_Word>> ShndxTableOrErr =
EF.getSHNDXTable(*DotSymtabShndxSec))
ShndxTable = *ShndxTableOrErr;
else
return ShndxTableOrErr.takeError();
}
Expected<const Elf_Shdr *> SectionOrErr =
EF.getSection(*ESym, *SymTabOrErr, ShndxTable);
if (!SectionOrErr)
@ -684,6 +694,16 @@ template <class ELFT>
Expected<section_iterator>
ELFObjectFile<ELFT>::getSymbolSection(const Elf_Sym *ESym,
const Elf_Shdr *SymTab) const {
ArrayRef<Elf_Word> ShndxTable;
if (DotSymtabShndxSec) {
// TODO: Test this error.
Expected<ArrayRef<Elf_Word>> ShndxTableOrErr =
EF.getSHNDXTable(*DotSymtabShndxSec);
if (!ShndxTableOrErr)
return ShndxTableOrErr.takeError();
ShndxTable = *ShndxTableOrErr;
}
auto ESecOrErr = EF.getSection(*ESym, SymTab, ShndxTable);
if (!ESecOrErr)
return ESecOrErr.takeError();
@ -984,7 +1004,7 @@ ELFObjectFile<ELFT>::create(MemoryBufferRef Object) {
const Elf_Shdr *DotDynSymSec = nullptr;
const Elf_Shdr *DotSymtabSec = nullptr;
ArrayRef<Elf_Word> ShndxTable;
const Elf_Shdr *DotSymtabShndxSec = nullptr;
for (const Elf_Shdr &Sec : *SectionsOrErr) {
switch (Sec.sh_type) {
case ELF::SHT_DYNSYM: {
@ -998,33 +1018,31 @@ ELFObjectFile<ELFT>::create(MemoryBufferRef Object) {
break;
}
case ELF::SHT_SYMTAB_SHNDX: {
auto TableOrErr = EF.getSHNDXTable(Sec);
if (!TableOrErr)
return TableOrErr.takeError();
ShndxTable = *TableOrErr;
if (!DotSymtabShndxSec)
DotSymtabShndxSec = &Sec;
break;
}
}
}
return ELFObjectFile<ELFT>(Object, EF, DotDynSymSec, DotSymtabSec,
ShndxTable);
DotSymtabShndxSec);
}
template <class ELFT>
ELFObjectFile<ELFT>::ELFObjectFile(MemoryBufferRef Object, ELFFile<ELFT> EF,
const Elf_Shdr *DotDynSymSec,
const Elf_Shdr *DotSymtabSec,
ArrayRef<Elf_Word> ShndxTable)
const Elf_Shdr *DotSymtabShndx)
: ELFObjectFileBase(
getELFType(ELFT::TargetEndianness == support::little, ELFT::Is64Bits),
Object),
EF(EF), DotDynSymSec(DotDynSymSec), DotSymtabSec(DotSymtabSec),
ShndxTable(ShndxTable) {}
DotSymtabShndxSec(DotSymtabShndx) {}
template <class ELFT>
ELFObjectFile<ELFT>::ELFObjectFile(ELFObjectFile<ELFT> &&Other)
: ELFObjectFile(Other.Data, Other.EF, Other.DotDynSymSec,
Other.DotSymtabSec, Other.ShndxTable) {}
Other.DotSymtabSec, Other.DotSymtabShndxSec) {}
template <class ELFT>
basic_symbol_iterator ELFObjectFile<ELFT>::symbol_begin() const {

4
test/Object/invalid.test
View File

@ -211,9 +211,9 @@ Sections:
## sizeof(.symtab_shndx) = (sizeof(.symtab) / entsize(.symtab)) * entsize(.symtab_shndx)
# RUN: yaml2obj %s --docnum=11 -o %t11
# RUN: not llvm-readobj --symbols %t11 2>&1 | FileCheck --check-prefix=INVALID-XINDEX-SIZE %s
# RUN: llvm-readobj --symbols %t11 2>&1 | FileCheck --check-prefix=INVALID-XINDEX-SIZE %s
# INVALID-XINDEX-SIZE: error: {{.*}}: SHT_SYMTAB_SHNDX has 2 entries, but the symbol table associated has 1
# INVALID-XINDEX-SIZE: warning: {{.*}}: SHT_SYMTAB_SHNDX has 2 entries, but the symbol table associated has 1
--- !ELF
FileHeader:

57
test/tools/llvm-readobj/ELF/symbol-shndx.test
View File

@ -254,3 +254,60 @@ Symbols:
Index: SHN_XINDEX
- Name: no_shndx2
Index: SHN_XINDEX
## Check we can dump symbols even when the number of entries in the
## SHT_SYMTAB_SHNDX section doesn't match the number of symbols in the symbol table.
# RUN: yaml2obj --docnum=4 %s -o %t4
# RUN: llvm-readelf --symbols %t4 2>&1 | FileCheck %s -DFILE=%t4 --check-prefix=SHNDX-ERR-GNU
# RUN: llvm-readobj --symbols %t4 2>&1 | FileCheck %s -DFILE=%t4 --check-prefix=SHNDX-ERR-LLVM
# SHNDX-ERR-GNU: warning: '[[FILE]]': SHT_SYMTAB_SHNDX has 3 entries, but the symbol table associated has 2
# SHNDX-ERR-GNU-EMPTY:
# SHNDX-ERR-GNU-NEXT: Symbol table '.symtab' contains 2 entries:
# SHNDX-ERR-GNU-NEXT: Num: Value Size Type Bind Vis Ndx Name
# SHNDX-ERR-GNU-NEXT: 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
# SHNDX-ERR-GNU-NEXT: warning: '[[FILE]]': extended symbol index (1) is past the end of the SHT_SYMTAB_SHNDX section of size 0
# SHNDX-ERR-GNU-NEXT: 1: 0000000000000000 0 NOTYPE LOCAL DEFAULT RSV[0xffff]
# SHNDX-ERR-GNU-EMPTY:
# SHNDX-ERR-GNU-NOT:{{.}}
# SHNDX-ERR-LLVM: warning: '[[FILE]]': SHT_SYMTAB_SHNDX has 3 entries, but the symbol table associated has 2
# SHNDX-ERR-LLVM: Format: elf64-unknown
# SHNDX-ERR-LLVM-NEXT: Arch: unknown
# SHNDX-ERR-LLVM-NEXT: AddressSize: 64bit
# SHNDX-ERR-LLVM-NEXT: LoadName: <Not found>
# SHNDX-ERR-LLVM-NEXT: Symbols [
# SHNDX-ERR-LLVM-NEXT: Symbol {
# SHNDX-ERR-LLVM-NEXT: Name: (0)
# SHNDX-ERR-LLVM-NEXT: Value: 0x0
# SHNDX-ERR-LLVM-NEXT: Size: 0
# SHNDX-ERR-LLVM-NEXT: Binding: Local (0x0)
# SHNDX-ERR-LLVM-NEXT: Type: None (0x0)
# SHNDX-ERR-LLVM-NEXT: Other: 0
# SHNDX-ERR-LLVM-NEXT: Section: Undefined (0x0)
# SHNDX-ERR-LLVM-NEXT: }
# SHNDX-ERR-LLVM-NEXT: Symbol {
# SHNDX-ERR-LLVM-NEXT: Name: (0)
# SHNDX-ERR-LLVM-NEXT: Value: 0x0
# SHNDX-ERR-LLVM-NEXT: Size: 0
# SHNDX-ERR-LLVM-NEXT: Binding: Local (0x0)
# SHNDX-ERR-LLVM-NEXT: Type: None (0x0)
# SHNDX-ERR-LLVM-NEXT: Other: 0
# SHNDX-ERR-LLVM-NEXT: warning: '[[FILE]]': extended symbol index (1) is past the end of the SHT_SYMTAB_SHNDX section of size 0
# SHNDX-ERR-LLVM-NEXT: Section: Reserved (0xFFFF)
# SHNDX-ERR-LLVM-NEXT: }
# SHNDX-ERR-LLVM-NEXT: ]
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Name: .symtab_shndx
Type: SHT_SYMTAB_SHNDX
Entries: [ 0, 1, 2 ]
Link: .symtab
Symbols:
- Index: SHN_XINDEX

2
test/tools/obj2yaml/ELF/sht-symtab-shndx.yaml
View File

@ -143,7 +143,7 @@ Symbols: []
# RUN: yaml2obj --docnum=6 %s -o %t6
# RUN: not obj2yaml %t6 2>&1 | FileCheck %s -DFILE=%t6 --check-prefix=CASE6
# CASE6: Error reading file: [[FILE]]: SHT_SYMTAB_SHNDX section is linked with SHT_PROGBITS section (expected SHT_SYMTAB/SHT_DYNSYM)
# CASE6: Error reading file: [[FILE]]: only SHT_SYMTAB_SHNDX associated with SHT_SYMTAB are supported
--- !ELF
FileHeader:

4
test/tools/yaml2obj/ELF/sht-symtab-shndx.yaml
View File

@ -107,9 +107,9 @@ Symbols:
## Check we can set a custom sh_entsize for SHT_SYMTAB_SHNDX section.
# RUN: yaml2obj --docnum=5 %s -o %t5
# RUN: not llvm-readelf -S 2>&1 %t5 | FileCheck %s -DFILE=%t5 --check-prefix=CASE5
# RUN: llvm-readelf -S 2>&1 %t5 | FileCheck %s -DFILE=%t5 --check-prefix=CASE5
# CASE5: error: '[[FILE]]': section [index 1] has an invalid sh_entsize: 2
# CASE5: warning: '[[FILE]]': section [index 1] has an invalid sh_entsize: 2
--- !ELF
FileHeader:

5
tools/llvm-readobj/ELFDumper.cpp
View File

@ -2026,7 +2026,10 @@ ELFDumper<ELFT>::ELFDumper(const object::ELFObjectFile<ELFT> &O,
}
break;
case ELF::SHT_SYMTAB_SHNDX:
ShndxTable = unwrapOrError(ObjF.getFileName(), Obj.getSHNDXTable(Sec));
if (Expected<ArrayRef<Elf_Word>> ShndxTableOrErr = Obj.getSHNDXTable(Sec))
ShndxTable = *ShndxTableOrErr;
else
this->reportUniqueWarning(ShndxTableOrErr.takeError());
break;
case ELF::SHT_GNU_versym:
if (!SymbolVersionSection)

1
unittests/Object/CMakeLists.txt
View File

@ -1,6 +1,7 @@
set(LLVM_LINK_COMPONENTS
BinaryFormat
Object
ObjectYAML
)
add_llvm_unittest(ObjectTests

35
unittests/Object/ELFObjectFileTest.cpp
View File

@ -8,6 +8,8 @@
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/ObjectYAML/yaml2obj.h"
#include "llvm/Support/YAMLTraits.h"
#include "llvm/Testing/Support/Error.h"
#include "gtest/gtest.h"
@ -291,9 +293,38 @@ TEST(ELFObjectFileTest, MachineTestForCSKY) {
checkFormatAndArch(D, Formats[I++], Triple::csky);
}
// ELF relative relocation type test.
TEST(ELFObjectFileTest, RelativeRelocationTypeTest) {
EXPECT_EQ(ELF::R_CKCORE_RELATIVE, getELFRelativeRelocationType(ELF::EM_CSKY));
}
template <class ELFT>
static Expected<ELFObjectFile<ELFT>> toBinary(SmallVectorImpl<char> &Storage,
StringRef Yaml) {
raw_svector_ostream OS(Storage);
yaml::Input YIn(Yaml);
if (!yaml::convertYAML(YIn, OS, [](const Twine &Msg) {}))
return createStringError(std::errc::invalid_argument,
"unable to convert YAML");
return ELFObjectFile<ELFT>::create(MemoryBufferRef(OS.str(), "dummyELF"));
}
// Check we are able to create an ELFObjectFile even when the content of the
// SHT_SYMTAB_SHNDX section can't be read properly.
TEST(ELFObjectFileTest, InvalidSymtabShndxTest) {
SmallString<0> Storage;
Expected<ELFObjectFile<ELF64LE>> ExpectedFile = toBinary<ELF64LE>(Storage, R"(
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Sections:
- Name: .symtab_shndx
Type: SHT_SYMTAB_SHNDX
Entries: [ 0 ]
ShSize: 0xFFFFFFFF
)");
ASSERT_THAT_EXPECTED(ExpectedFile, Succeeded());
}