[llvm-objcopy] - Report SHT_GROUP sections with invalid alignment.
This patch fixes the reason of ubsan failure (UB detected)
happened after landing the D59638 (I had to revert it).
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap-ubsan/builds/11760/steps/check-llvm%20ubsan/logs/stdio)
Problem is the following. Our implementation of GroupSection assumes that
its address is 4 bytes aligned when writes it:
template <class ELFT>
void ELFSectionWriter<ELFT>::visit(const GroupSection &Sec) {
ELF::Elf32_Word *Buf =
reinterpret_cast<ELF::Elf32_Word *>(Out.getBufferStart() + Sec.Offset);
...
But the test case for D59638 did not set AddressAlign in YAML. So address was
not 4 bytes aligned since Sec.Offset was odd. That triggered the issue.
This patch teaches llvm-objcopy to report an error for such sections (which should
not met in reality), what is better than having UB.
Differential revision: https://reviews.llvm.org/D59695
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@356853 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/tools/llvm-objcopy/ELF/group-addr-misaligned.test b/test/tools/llvm-objcopy/ELF/group-addr-misaligned.test
new file mode 100644
index 0000000..43a6028
--- /dev/null
+++ b/test/tools/llvm-objcopy/ELF/group-addr-misaligned.test
@@ -0,0 +1,38 @@
+# RUN: yaml2obj %s > %t
+# RUN: not llvm-objcopy %t %t2 2>&1 | FileCheck %s
+# CHECK: error: Invalid alignment 1 of group section .group.
+
+# In this test, we check that llvm-objcopy reports an error
+# for SHT_GROUP section with invalid alignment (not a multiple of 4).
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+Sections:
+## It is not important for passing the test case to have this placeholder,
+## but having it would trigger ubsan failure when writing the group section
+## into a file if the error tested would not be reported by llvm-objcopy.
+ - Name: .placeholder
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x0000000000000001
+ Content: "00"
+ - Name: .group
+ Type: SHT_GROUP
+ Link: .symtab
+ AddressAlign: 0x0000000000000001
+ Info: foo
+ Members:
+ - SectionOrType: GRP_COMDAT
+ - SectionOrType: .text.foo
+ - Name: .text.foo
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR, SHF_GROUP ]
+ AddressAlign: 0x0000000000000001
+Symbols:
+ Local:
+ - Name: foo
+ Section: .group
diff --git a/tools/llvm-objcopy/ELF/Object.cpp b/tools/llvm-objcopy/ELF/Object.cpp
index ccc6efa..39bee85 100644
--- a/tools/llvm-objcopy/ELF/Object.cpp
+++ b/tools/llvm-objcopy/ELF/Object.cpp
@@ -949,6 +949,9 @@
template <class ELFT>
void ELFBuilder<ELFT>::initGroupSection(GroupSection *GroupSec) {
+ if (GroupSec->Align % sizeof(ELF::Elf32_Word) != 0)
+ error("Invalid alignment " + Twine(GroupSec->Align) + " of group section " +
+ GroupSec->Name);
auto SecTable = Obj.sections();
auto SymTab = SecTable.template getSectionOfType<SymbolTableSection>(
GroupSec->Link,
