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Use unaligned read to fix UB. NFC. 

We were casting a potentially unaligned pointer to uint32_t and
dereferencing.  As the pointer ultimately comes from the object file,
there's no way to guarantee alignment, so use the little32_t read instead.

Also, little32_t knows about endianness, so in theory this may have broken on
big endian machines.

llvm-svn: 264231
This commit is contained in:
Pete Cooper 2016-03-24 01:03:44 +00:00
parent 6278f933a8
commit a13f62f5f8
1 changed files with 4 additions and 3 deletions
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7
lld/lib/ReaderWriter/MachO/ArchHandler_arm64.cpp
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@ -477,7 +477,6 @@ std::error_code ArchHandler_arm64::getPairReferenceInfo(
FindAtomBySymbolIndex atomFromSymbolIndex, Reference::KindValue *kind,
const lld::Atom **target, Reference::Addend *addend) {
const uint8_t *fixupContent = &inAtom->rawContent()[offsetInAtom];
const uint32_t *cont32 = reinterpret_cast<const uint32_t *>(fixupContent);
switch (relocPattern(reloc1) << 16 | relocPattern(reloc2)) {
case ((ARM64_RELOC_ADDEND | rLength4) << 16 |
ARM64_RELOC_BRANCH26 | rPcRel | rExtern | rLength4):
@ -496,13 +495,15 @@ std::error_code ArchHandler_arm64::getPairReferenceInfo(
*addend = reloc1.symbol;
return std::error_code();
case ((ARM64_RELOC_ADDEND | rLength4) << 16 |
ARM64_RELOC_PAGEOFF12 | rExtern | rLength4):
ARM64_RELOC_PAGEOFF12 | rExtern | rLength4): {
// ex: ldr w0, [x1, _foo@PAGEOFF]
*kind = offset12KindFromInstruction(*cont32);
uint32_t cont32 = (int32_t)*(const little32_t *)fixupContent;
*kind = offset12KindFromInstruction(cont32);
if (auto ec = atomFromSymbolIndex(reloc2.symbol, target))
return ec;
*addend = reloc1.symbol;
return std::error_code();
}
case ((ARM64_RELOC_SUBTRACTOR | rExtern | rLength8) << 16 |
ARM64_RELOC_UNSIGNED | rExtern | rLength8):
// ex: .quad _foo - .