| From c314f5ede8249ef20fff1de45c2c31156b1950d4 Mon Sep 17 00:00:00 2001 |
| From: Peter Collingbourne <peter@pcc.me.uk> |
| Date: Wed, 16 Dec 2020 17:53:20 -0800 |
| Subject: [PATCH] ObjectFileELF: Test whether reloc_header is non-null instead |
| of asserting. |
| |
| It is possible for the GetSectionHeaderByIndex lookup to fail because |
| the previous FindSectionContainingFileAddress lookup found a segment |
| instead of a section. This is possible if the binary does not have |
| a PLT (which means that lld will in some circumstances set DT_JMPREL |
| to 0, which is typically an address that is part of the ELF headers |
| and not in a section) and may also be possible if the section headers |
| have been stripped. To handle this possibility, replace the assert |
| with an if. |
| |
| Differential Revision: https://reviews.llvm.org/D93438 |
| --- |
| .../Plugins/ObjectFile/ELF/ObjectFileELF.cpp | 14 +- |
| .../Shell/ObjectFile/ELF/null-jmprel.yaml | 148 ++++++++++++++++++ |
| 2 files changed, 155 insertions(+), 7 deletions(-) |
| create mode 100644 lldb/test/Shell/ObjectFile/ELF/null-jmprel.yaml |
| |
| diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp |
| index cad9ce218b10..df0586367832 100644 |
| --- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp |
| +++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp |
| @@ -2770,14 +2770,14 @@ Symtab *ObjectFileELF::GetSymtab() { |
| user_id_t reloc_id = reloc_section->GetID(); |
| const ELFSectionHeaderInfo *reloc_header = |
| GetSectionHeaderByIndex(reloc_id); |
| - assert(reloc_header); |
| + if (reloc_header) { |
| + if (m_symtab_up == nullptr) |
| + m_symtab_up = |
| + std::make_unique<Symtab>(reloc_section->GetObjectFile()); |
| |
| - if (m_symtab_up == nullptr) |
| - m_symtab_up = |
| - std::make_unique<Symtab>(reloc_section->GetObjectFile()); |
| - |
| - ParseTrampolineSymbols(m_symtab_up.get(), symbol_id, reloc_header, |
| - reloc_id); |
| + ParseTrampolineSymbols(m_symtab_up.get(), symbol_id, reloc_header, |
| + reloc_id); |
| + } |
| } |
| } |
| |
| diff --git a/lldb/test/Shell/ObjectFile/ELF/null-jmprel.yaml b/lldb/test/Shell/ObjectFile/ELF/null-jmprel.yaml |
| new file mode 100644 |
| index 000000000000..ae151ba8cdc1 |
| --- /dev/null |
| +++ b/lldb/test/Shell/ObjectFile/ELF/null-jmprel.yaml |
| @@ -0,0 +1,148 @@ |
| +# RUN: yaml2obj %s -o %t |
| +# RUN: lldb-test symbols %t | FileCheck %s |
| + |
| +# CHECK: _DYNAMIC |
| +# CHECK: _start |
| + |
| +--- !ELF |
| +FileHeader: |
| + Class: ELFCLASS64 |
| + Data: ELFDATA2LSB |
| + Type: ET_DYN |
| + Machine: EM_X86_64 |
| + Entry: 0x1000 |
| +ProgramHeaders: |
| + - Type: PT_PHDR |
| + Flags: [ PF_R ] |
| + VAddr: 0x40 |
| + Align: 0x8 |
| + - Type: PT_LOAD |
| + Flags: [ PF_R ] |
| + FirstSec: .dynsym |
| + LastSec: .dynstr |
| + Align: 0x1000 |
| + - Type: PT_LOAD |
| + Flags: [ PF_X, PF_R ] |
| + FirstSec: .text |
| + LastSec: .text |
| + VAddr: 0x1000 |
| + Align: 0x1000 |
| + - Type: PT_LOAD |
| + Flags: [ PF_W, PF_R ] |
| + FirstSec: .data |
| + LastSec: .bss |
| + VAddr: 0x2000 |
| + Align: 0x1000 |
| + - Type: PT_DYNAMIC |
| + Flags: [ PF_W, PF_R ] |
| + FirstSec: .data |
| + LastSec: .dynamic |
| + VAddr: 0x2000 |
| + Align: 0x8 |
| + - Type: PT_GNU_RELRO |
| + Flags: [ PF_R ] |
| + FirstSec: .data |
| + LastSec: .bss |
| + VAddr: 0x2000 |
| + - Type: PT_GNU_STACK |
| + Flags: [ PF_W, PF_R ] |
| + Align: 0x0 |
| +Sections: |
| + - Name: .dynsym |
| + Type: SHT_DYNSYM |
| + Flags: [ SHF_ALLOC ] |
| + Address: 0x1C8 |
| + Link: .dynstr |
| + AddressAlign: 0x8 |
| + EntSize: 0x18 |
| + - Name: .gnu.hash |
| + Type: SHT_GNU_HASH |
| + Flags: [ SHF_ALLOC ] |
| + Address: 0x1F8 |
| + Link: .dynsym |
| + AddressAlign: 0x8 |
| + Header: |
| + SymNdx: 0x1 |
| + Shift2: 0x6 |
| + BloomFilter: [ 0x4000000000100 ] |
| + HashBuckets: [ 0x1 ] |
| + HashValues: [ 0xEDDB6233 ] |
| + - Name: .hash |
| + Type: SHT_HASH |
| + Flags: [ SHF_ALLOC ] |
| + Address: 0x218 |
| + Link: .dynsym |
| + AddressAlign: 0x4 |
| + Bucket: [ 1, 0 ] |
| + Chain: [ 0, 0 ] |
| + - Name: .dynstr |
| + Type: SHT_STRTAB |
| + Flags: [ SHF_ALLOC ] |
| + Address: 0x230 |
| + AddressAlign: 0x1 |
| + - Name: .text |
| + Type: SHT_PROGBITS |
| + Flags: [ SHF_ALLOC, SHF_EXECINSTR ] |
| + Address: 0x1000 |
| + AddressAlign: 0x1 |
| + Offset: 0x1000 |
| + Content: C3 |
| + - Name: .data |
| + Type: SHT_PROGBITS |
| + Flags: [ SHF_WRITE, SHF_ALLOC ] |
| + Address: 0x2000 |
| + AddressAlign: 0x1 |
| + Offset: 0x2000 |
| + - Name: .dynamic |
| + Type: SHT_DYNAMIC |
| + Flags: [ SHF_WRITE, SHF_ALLOC ] |
| + Address: 0x2000 |
| + Link: .dynstr |
| + AddressAlign: 0x8 |
| + Entries: |
| + - Tag: DT_SYMTAB |
| + Value: 0x1C8 |
| + - Tag: DT_SYMENT |
| + Value: 0x18 |
| + - Tag: DT_STRTAB |
| + Value: 0x230 |
| + - Tag: DT_STRSZ |
| + Value: 0x8 |
| + - Tag: DT_GNU_HASH |
| + Value: 0x1F8 |
| + - Tag: DT_HASH |
| + Value: 0x218 |
| + - Tag: DT_JMPREL |
| + Value: 0x0 |
| + - Tag: DT_PLTRELSZ |
| + Value: 0x0 |
| + - Tag: DT_NULL |
| + Value: 0x0 |
| + - Name: .bss |
| + Type: SHT_NOBITS |
| + Flags: [ SHF_WRITE, SHF_ALLOC ] |
| + Address: 0x3000 |
| + AddressAlign: 0x1 |
| + - Name: .comment |
| + Type: SHT_PROGBITS |
| + Flags: [ SHF_MERGE, SHF_STRINGS ] |
| + AddressAlign: 0x1 |
| + EntSize: 0x1 |
| + Content: 4C696E6B65723A204C4C4420372E302E3000 |
| +Symbols: |
| + - Name: _DYNAMIC |
| + Section: .dynamic |
| + Value: 0x2000 |
| + Other: [ STV_HIDDEN ] |
| + - Name: _start |
| + Type: STT_FUNC |
| + Section: .text |
| + Binding: STB_GLOBAL |
| + Value: 0x1000 |
| +DynamicSymbols: |
| + - Name: _start |
| + Type: STT_FUNC |
| + Section: .text |
| + Binding: STB_GLOBAL |
| + Value: 0x1000 |
| +... |
| -- |
| 2.31.0.291.g576ba9dcdaf-goog |
| |
