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[llvm-readobj] - Verify the location of program headers better. 

This improves condition in the ELFFile::program_headers().
Previously if was possible to read the headers from the wrong place when
the value of e_phoff was so large that computation overflowed.

Differential revision: https://reviews.llvm.org/D83774
This commit is contained in:
Georgii Rymar 2020-07-14 17:14:06 +03:00
parent f6eb5daa16
commit 327c445035
2 changed files with 36 additions and 7 deletions
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12
llvm/include/llvm/Object/ELF.h
View File

@ -205,16 +205,18 @@ public:
if (getHeader()->e_phnum && getHeader()->e_phentsize != sizeof(Elf_Phdr))
return createError("invalid e_phentsize: " +
Twine(getHeader()->e_phentsize));
if (getHeader()->e_phoff +
(getHeader()->e_phnum * getHeader()->e_phentsize) >
getBufSize())
uint64_t HeadersSize =
(uint64_t)getHeader()->e_phnum * getHeader()->e_phentsize;
uint64_t PhOff = getHeader()->e_phoff;
if (PhOff + HeadersSize < PhOff || PhOff + HeadersSize > getBufSize())
return createError("program headers are longer than binary of size " +
Twine(getBufSize()) + ": e_phoff = 0x" +
Twine::utohexstr(getHeader()->e_phoff) +
", e_phnum = " + Twine(getHeader()->e_phnum) +
", e_phentsize = " + Twine(getHeader()->e_phentsize));
auto *Begin =
reinterpret_cast<const Elf_Phdr *>(base() + getHeader()->e_phoff);
auto *Begin = reinterpret_cast<const Elf_Phdr *>(base() + PhOff);
return makeArrayRef(Begin, Begin + getHeader()->e_phnum);
}

31
llvm/test/tools/llvm-readobj/ELF/gnu-phdrs.test
View File

@ -356,7 +356,8 @@ ProgramHeaders:
Offset: 0xAABBCCDDEEFF1122
## Check we report a warning when we are unable to read program headers.
# RUN: yaml2obj --docnum=3 %s -o %t.phdr.err
## Case A: the e_phentsize field is invalid.
# RUN: yaml2obj --docnum=3 -DPHENTSIZE=1 %s -o %t.phdr.err
# RUN: llvm-readelf --program-headers %t.phdr.err 2>&1 | \
# RUN: FileCheck %s -DFILE=%t.phdr.err --check-prefix=WARN-PHENTSIZE
@ -373,7 +374,8 @@ FileHeader:
Data: ELFDATA2LSB
Type: ET_EXEC
Machine: EM_X86_64
EPhEntSize: 1
EPhEntSize: [[PHENTSIZE=56]]
EPhOff: [[PHOFF=64]]
Sections:
- Name: .foo
Type: SHT_PROGBITS
@ -381,3 +383,28 @@ ProgramHeaders:
- Type: PT_PHDR
Sections:
- Section: .foo
## Case B: the value of the e_phoff field is invalid.
## Check that we do not report a warning when the program header table ends right before the end of the file.
## 0x160 + size of headers (56) == file size.
# RUN: yaml2obj --docnum=3 -DPHOFF=0x160 %s -o %t.phdr.no.err2
# RUN: llvm-readelf %t.phdr.no.err2 --program-headers 2>&1 | FileCheck %s --implicit-check-not=warning:
## Check we report a warning when e_phoff goes 1 byte past the end of the file.
# RUN: yaml2obj --docnum=3 -DPHOFF=0x161 %s -o %t.phdr.err2
# RUN: llvm-readelf --program-headers %t.phdr.err2 2>&1 | \
# RUN: FileCheck %s -DFILE=%t.phdr.err2 --check-prefix=WARN-PHOFF -DOFF=0x161
# WARN-PHOFF: Program Headers:
# WARN-PHOFF-NEXT: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
# WARN-PHOFF-NEXT: warning: '[[FILE]]': unable to dump program headers: program headers are longer than binary of size 408: e_phoff = [[OFF]], e_phnum = 1, e_phentsize = 56
# WARN-PHOFF: Section to Segment mapping:
# WARN-PHOFF-NEXT: Segment Sections...
# WARN-PHOFF-NEXT: warning: '[[FILE]]': can't read program headers to build section to segment mapping: program headers are longer than binary of size 408: e_phoff = [[OFF]], e_phnum = 1, e_phentsize = 56
## Check we report a warning when the value of e_phoff is so large that
## e_phoff + e_phnum * e_phentsize > UINT64_MAX.
# RUN: yaml2obj --docnum=3 -DPHOFF=0xffffffffffffffff %s -o %t.phdr.err3
# RUN: llvm-readelf --program-headers %t.phdr.err3 2>&1 | \
# RUN: FileCheck %s -DFILE=%t.phdr.err3 --check-prefix=WARN-PHOFF -DOFF=0xffffffffffffffff