Huaisi Xu created THRIFT-3821:
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Summary: TMemoryBuffer buffer may overflow when resizing
Key: THRIFT-3821
URL: https://issues.apache.org/jira/browse/THRIFT-3821
Project: Thrift
Issue Type: Bug
Affects Versions: 0.9.3
Reporter: Huaisi Xu
Priority: Critical
uint32_t new_size = bufferSize_;
while (len > avail) {
new_size = new_size > 0 ? new_size * 2 : 1;
avail = available_write() + (new_size - bufferSize_);
}
// Allocate into a new pointer so we don't bork ours if it fails.
uint8_t* new_buffer = static_cast<uint8_t*>(std::realloc(buffer_, new_size));
if (new_buffer == NULL) {
throw std::bad_alloc();
}
rBase_ = new_buffer + (rBase_ - buffer_);
rBound_ = new_buffer + (rBound_ - buffer_);
wBase_ = new_buffer + (wBase_ - buffer_);
wBound_ = new_buffer + new_size;
buffer_ = new_buffer;
bufferSize_ = new_size;
If old bufferSize_ is lager than 2gb, then calculating new size will overflow.
i.e. if bufferSize_ = 3355443200, then new buffer size will be 2415919104,
which is less than old size.
However, avail = available_write() + (new_size - bufferSize_) overflows again,
so we will end up with an shrinked buffer.
What is worse is that after
wBase_ = new_buffer + (wBase_ - buffer_);
wBound_ = new_buffer + new_size;
wBase_ stays the same, but wBound_ becomes lower than it. What happens next is
that uint32_t avail = available_write() may overflow every time subsequently.
and thrift writes to unknown memory.
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