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Prevent unaligned memory read in parseMinidumpString 

Summary:
It's possible to hit an unaligned memory read when reading `source_length` as the `data` array is only aligned with 2 bytes (it's actually a UTF16 array). This patch memcpy's `source_length` into a local variable to prevent this:

```
MinidumpTypes.cpp:49:23: runtime error: load of misaligned address 0x7f0f4792692a for type 'const uint32_t' (aka 'const unsigned int'), which requires 4 byte alignment
```

Reviewers: dvlahovski, zturner, davide

Reviewed By: davide

Subscribers: davide, lldb-commits

Differential Revision: https://reviews.llvm.org/D42348

llvm-svn: 323181
This commit is contained in:
Raphael Isemann 2018-01-23 08:04:27 +00:00
parent e57620308e
commit acc48f3e1d
1 changed files with 10 additions and 5 deletions
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15
lldb/source/Plugins/Process/minidump/MinidumpTypes.cpp
View File

@ -44,9 +44,14 @@ llvm::Optional<std::string>
lldb_private::minidump::parseMinidumpString(llvm::ArrayRef<uint8_t> &data) {
std::string result;
const uint32_t *source_length;
Status error = consumeObject(data, source_length);
if (error.Fail() || *source_length > data.size() || *source_length % 2 != 0)
const uint32_t *source_length_ptr;
Status error = consumeObject(data, source_length_ptr);
// Copy non-aligned source_length data into aligned memory.
uint32_t source_length;
std::memcpy(&source_length, source_length_ptr, sizeof(source_length));
if (error.Fail() || source_length > data.size() || source_length % 2 != 0)
return llvm::None;
auto source_start = reinterpret_cast<const llvm::UTF16 *>(data.data());
@ -54,9 +59,9 @@ lldb_private::minidump::parseMinidumpString(llvm::ArrayRef<uint8_t> &data) {
// we need the length of the string in UTF-16 characters/code points (16 bits
// per char)
// that's why it's divided by 2
const auto source_end = source_start + (*source_length) / 2;
const auto source_end = source_start + source_length / 2;
// resize to worst case length
result.resize(UNI_MAX_UTF8_BYTES_PER_CODE_POINT * (*source_length) / 2);
result.resize(UNI_MAX_UTF8_BYTES_PER_CODE_POINT * source_length / 2);
auto result_start = reinterpret_cast<llvm::UTF8 *>(&result[0]);
const auto result_end = result_start + result.size();
llvm::ConvertUTF16toUTF8(&source_start, source_end, &result_start, result_end,