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[llvm-readobj] - Do not crash when an invalid .eh_frame_hdr is dumped using --unwind.

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When the p_offset/p_filesz of the PT_GNU_EH_FRAME is invalid
(e.g larger than the file size) then llvm-readobj might crash.

This patch fixes the issue. I've introduced `ELFFile<ELFT>::getSegmentContent`
method, which is very similar to `ELFFile<ELFT>::getSectionContentsAsArray` one.

Differential revision: https://reviews.llvm.org/D80380
This commit is contained in:
Georgii Rymar 2020-05-21 17:29:18 +03:00
parent f14df40a71
commit dc0839500a
3 changed files with 107 additions and 16 deletions
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32
include/llvm/Object/ELF.h
View File

@ -64,6 +64,17 @@ std::string getSecIndexForError(const ELFFile<ELFT> *Obj,
return "[unknown index]";
}
template <class ELFT>
std::string getPhdrIndexForError(const ELFFile<ELFT> *Obj,
const typename ELFT::Phdr *Phdr) {
auto Headers = Obj->program_headers();
if (Headers)
return ("[index " + Twine(Phdr - &Headers->front()) + "]").str();
// See comment in the getSecIndexForError() above.
llvm::consumeError(Headers.takeError());
return "[unknown index]";
}
static inline Error defaultWarningHandler(const Twine &Msg) {
return createError(Msg);
}
@ -299,6 +310,7 @@ public:
template <typename T>
Expected<ArrayRef<T>> getSectionContentsAsArray(const Elf_Shdr *Sec) const;
Expected<ArrayRef<uint8_t>> getSectionContents(const Elf_Shdr *Sec) const;
Expected<ArrayRef<uint8_t>> getSegmentContents(const Elf_Phdr *Phdr) const;
};
using ELF32LEFile = ELFFile<ELF32LE>;
@ -422,6 +434,26 @@ ELFFile<ELFT>::getSectionContentsAsArray(const Elf_Shdr *Sec) const {
return makeArrayRef(Start, Size / sizeof(T));
}
template <class ELFT>
Expected<ArrayRef<uint8_t>>
ELFFile<ELFT>::getSegmentContents(const Elf_Phdr *Phdr) const {
uintX_t Offset = Phdr->p_offset;
uintX_t Size = Phdr->p_filesz;
if (std::numeric_limits<uintX_t>::max() - Offset < Size)
return createError("program header " + getPhdrIndexForError(this, Phdr) +
" has a p_offset (0x" + Twine::utohexstr(Offset) +
") + p_filesz (0x" + Twine::utohexstr(Size) +
") that cannot be represented");
if (Offset + Size > Buf.size())
return createError("program header " + getPhdrIndexForError(this, Phdr) +
" has a p_offset (0x" + Twine::utohexstr(Offset) +
") + p_filesz (0x" + Twine::utohexstr(Size) +
") that is greater than the file size (0x" +
Twine::utohexstr(Buf.size()) + ")");
return makeArrayRef(base() + Offset, Size);
}
template <class ELFT>
Expected<ArrayRef<uint8_t>>
ELFFile<ELFT>::getSectionContents(const Elf_Shdr *Sec) const {

61
test/tools/llvm-readobj/ELF/unwind.test
View File

@ -262,3 +262,64 @@ Sections:
Type: SHT_PROGBITS
## Length is set to 0xFF, though the actual section length is 4.
Content: "FF000000"
## Check we report an error when we can't read the content of the .eh_frame section.
## Case A: test we report an error when the p_offset of the PT_GNU_EH_FRAME
## is invalid (goes past the end of the file).
# RUN: yaml2obj --docnum=4 %s -o %t4 -DOFFSET=0xffff0000 -DSIZE=0x1 -DBITS=32
# RUN: not llvm-readobj --unwind %t4 2>&1 \
# RUN: | FileCheck %s -DFILE=%t4 --check-prefix=BROKEN-CONTENT -DOFFSET=0xffff0000 -DSIZE=0x1
# RUN: yaml2obj --docnum=4 %s -o %t5 -DOFFSET=0x1 -DSIZE=0xffff0000 -DBITS=32
# RUN: not llvm-readobj --unwind %t5 2>&1 \
# RUN: | FileCheck %s -DFILE=%t5 --check-prefix=BROKEN-CONTENT -DOFFSET=0x1 -DSIZE=0xffff0000
# BROKEN-CONTENT: EHFrameHeader {
# BROKEN-CONTENT-NEXT: Address: 0x0
# BROKEN-CONTENT-NEXT: Offset: [[OFFSET]]
# BROKEN-CONTENT-NEXT: Size: [[SIZE]]
# BROKEN-CONTENT-NEXT: Corresponding Section:
# BROKEN-CONTENT-NEXT: error: '[[FILE]]': program header [index 0] has a p_offset ([[OFFSET]]) + p_filesz ([[SIZE]]) that is greater than the file size (0xe0)
--- !ELF
FileHeader:
Class: ELFCLASS[[BITS]]
Data: ELFDATA2LSB
Type: ET_EXEC
Machine: EM_NONE
ProgramHeaders:
- Type: PT_GNU_EH_FRAME
MemSize: [[SIZE]]
FileSize: [[SIZE]]
Offset: [[OFFSET]]
Sections: []
## Case B: test we report an error when the file size of the PT_GNU_EH_FRAME
## is invalid (goes past the end of the file).
# RUN: yaml2obj --docnum=4 %s -o %t6 -DOFFSET=0x100 -DSIZE=0xffff0000 -DBITS=32
# RUN: not llvm-readobj --unwind %t6 2>&1 \
# RUN: | FileCheck %s -DFILE=%t6 --check-prefix=BROKEN-CONTENT -DOFFSET=0x100 -DSIZE=0xffff0000
## Case C: test we report an error when the offset + the file size of the PT_GNU_EH_FRAME is so large a
## value that it overflows the platform address size type.
# RUN: yaml2obj --docnum=4 %s -o %t7 -DOFFSET=0x1 -DSIZE=0xffffffff -DBITS=32
# RUN: not llvm-readobj --unwind %t7 2>&1 | FileCheck %s -DFILE=%t7 --check-prefix=BROKEN-CONTENT2 -DOFFSET=0x1 -DSIZE=0xffffffff
# RUN: yaml2obj --docnum=4 %s -o %t8 -DOFFSET=0xffffffff -DSIZE=0x1 -DBITS=32
# RUN: not llvm-readobj --unwind %t8 2>&1 | FileCheck %s -DFILE=%t8 --check-prefix=BROKEN-CONTENT2 -DOFFSET=0xffffffff -DSIZE=0x1
# RUN: yaml2obj --docnum=4 %s -o %t9 -DOFFSET=0x1 -DSIZE=0xffffffffffffffff -DBITS=64
# RUN: not llvm-readelf --unwind %t9 2>&1 | FileCheck %s -DFILE=%t9 --check-prefix=BROKEN-CONTENT2 -DOFFSET=0x1 -DSIZE=0xffffffffffffffff
# RUN: yaml2obj --docnum=4 %s -o %t10 -DOFFSET=0xffffffffffffffff -DSIZE=0x1 -DBITS=64
# RUN: not llvm-readelf --unwind %t10 2>&1 | FileCheck %s -DFILE=%t10 --check-prefix=BROKEN-CONTENT2 -DOFFSET=0xffffffffffffffff -DSIZE=0x1
# BROKEN-CONTENT2: EHFrameHeader {
# BROKEN-CONTENT2-NEXT: Address: 0x0
# BROKEN-CONTENT2-NEXT: Offset: [[OFFSET]]
# BROKEN-CONTENT2-NEXT: Size: [[SIZE]]
# BROKEN-CONTENT2-NEXT: Corresponding Section:
# BROKEN-CONTENT2-NEXT: error: '[[FILE]]': program header [index 0] has a p_offset ([[OFFSET]]) + p_filesz ([[SIZE]]) that cannot be represented

30
tools/llvm-readobj/DwarfCFIEHPrinter.h
View File

@ -33,8 +33,7 @@ class PrinterContext {
ScopedPrinter &W;
const object::ELFObjectFile<ELFT> *ObjF;
void printEHFrameHdr(uint64_t Offset, uint64_t Address, uint64_t Size) const;
void printEHFrameHdr(const typename ELFT::Phdr *EHFramePHdr) const;
void printEHFrame(const typename ELFT::Shdr *EHFrameShdr) const;
public:
@ -60,7 +59,6 @@ findSectionByAddress(const object::ELFObjectFile<ELFT> *ObjF, uint64_t Addr) {
template <typename ELFT>
void PrinterContext<ELFT>::printUnwindInformation() const {
const object::ELFFile<ELFT> *Obj = ObjF->getELFFile();
const typename ELFT::Phdr *EHFramePhdr = nullptr;
auto PHs = Obj->program_headers();
if (Error E = PHs.takeError())
@ -68,19 +66,15 @@ void PrinterContext<ELFT>::printUnwindInformation() const {
for (const auto &Phdr : *PHs) {
if (Phdr.p_type == ELF::PT_GNU_EH_FRAME) {
EHFramePhdr = &Phdr;
if (Phdr.p_memsz != Phdr.p_filesz)
reportError(object::createError(
"p_memsz does not match p_filesz for GNU_EH_FRAME"),
ObjF->getFileName());
printEHFrameHdr(&Phdr);
break;
}
}
if (EHFramePhdr)
printEHFrameHdr(EHFramePhdr->p_offset, EHFramePhdr->p_vaddr,
EHFramePhdr->p_memsz);
auto Sections = Obj->sections();
if (Error E = Sections.takeError())
reportError(std::move(E), ObjF->getFileName());
@ -96,16 +90,16 @@ void PrinterContext<ELFT>::printUnwindInformation() const {
}
template <typename ELFT>
void PrinterContext<ELFT>::printEHFrameHdr(uint64_t EHFrameHdrOffset,
uint64_t EHFrameHdrAddress,
uint64_t EHFrameHdrSize) const {
void PrinterContext<ELFT>::printEHFrameHdr(const typename ELFT::Phdr *EHFramePHdr) const {
DictScope L(W, "EHFrameHeader");
uint64_t EHFrameHdrAddress = EHFramePHdr->p_vaddr;
W.startLine() << format("Address: 0x%" PRIx64 "\n", EHFrameHdrAddress);
W.startLine() << format("Offset: 0x%" PRIx64 "\n", EHFrameHdrOffset);
W.startLine() << format("Size: 0x%" PRIx64 "\n", EHFrameHdrSize);
W.startLine() << format("Offset: 0x%" PRIx64 "\n", (uint64_t)EHFramePHdr->p_offset);
W.startLine() << format("Size: 0x%" PRIx64 "\n", (uint64_t)EHFramePHdr->p_memsz);
const object::ELFFile<ELFT> *Obj = ObjF->getELFFile();
const auto *EHFrameHdrShdr = findSectionByAddress(ObjF, EHFrameHdrAddress);
const typename ELFT::Shdr *EHFrameHdrShdr =
findSectionByAddress(ObjF, EHFramePHdr->p_vaddr);
if (EHFrameHdrShdr) {
auto SectionName = Obj->getSectionName(EHFrameHdrShdr);
if (Error E = SectionName.takeError())
@ -114,7 +108,11 @@ void PrinterContext<ELFT>::printEHFrameHdr(uint64_t EHFrameHdrOffset,
W.printString("Corresponding Section", *SectionName);
}
DataExtractor DE(makeArrayRef(Obj->base() + EHFrameHdrOffset, EHFrameHdrSize),
Expected<ArrayRef<uint8_t>> Content = Obj->getSegmentContents(EHFramePHdr);
if (!Content)
reportError(Content.takeError(), ObjF->getFileName());
DataExtractor DE(*Content,
ELFT::TargetEndianness == support::endianness::little,
ELFT::Is64Bits ? 8 : 4);
@ -154,7 +152,7 @@ void PrinterContext<ELFT>::printEHFrameHdr(uint64_t EHFrameHdrOffset,
unsigned NumEntries = 0;
uint64_t PrevPC = 0;
while (Offset + 8 <= EHFrameHdrSize && NumEntries < FDECount) {
while (Offset + 8 <= EHFramePHdr->p_memsz && NumEntries < FDECount) {
DictScope D(W, std::string("entry ") + std::to_string(NumEntries));
auto InitialPC = DE.getSigned(&Offset, 4) + EHFrameHdrAddress;