Out-of-bounds read for corrupt view offsets in BaseVariableWidthViewVector #1217

Describe the bug

ViewVarCharVector/ViewVarBinaryVector store values longer than INLINE_SIZE (12 bytes) out of line, encoding a data-buffer index and an offset inline in the view buffer. When a vector is loaded from an IPC stream these fields come straight from the input.

BaseVariableWidthViewVector dereferences them verbatim in getData, getDataPointer, hashCode, copyFromNotNull and splitAndTransferViewBufferAndDataBuffer, e.g.

dataBuffers.get(bufferIndex).getBytes(dataOffset, result, 0, dataLength);

Nothing checks that bufferIndex is in range or that dataOffset + dataLength fits inside the referenced data buffer. A crafted view whose offset/length points past the data buffer produces an out-of-bounds read: with the default bounds checking it throws IndexOutOfBoundsException, but with arrow.enable_unsafe_memory_access=true (commonly set in production) it reads arbitrary native heap into the returned value.

Component(s)

Java