Author: teemperor Date: Tue Jan 23 00:04:27 2018 New Revision: 323181 URL: http://llvm.org/viewvc/llvm-project?rev=323181&view=rev Log: 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 Modified: lldb/trunk/source/Plugins/Process/minidump/MinidumpTypes.cpp Modified: lldb/trunk/source/Plugins/Process/minidump/MinidumpTypes.cpp URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/Process/minidump/MinidumpTypes.cpp?rev=323181&r1=323180&r2=323181&view=diff ============================================================================== --- lldb/trunk/source/Plugins/Process/minidump/MinidumpTypes.cpp (original) +++ lldb/trunk/source/Plugins/Process/minidump/MinidumpTypes.cpp Tue Jan 23 00:04:27 2018 @@ -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::parseMinidumpStr // 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, _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
