Details
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Bug
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Status: Open
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Minor
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Resolution: Unresolved
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0.23.0, 2.5.0
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None
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None
Description
In DataInputByteBuffer$Buffer class, the fields bidx and buffers, etc are unsynchronized when used in read() and reset() function. In certain circumstances, e.g., the reset() is invoked in a loop, the unsynchronized bidx and buffers can trigger a concurrency bug.
Here is the code snippet.
ByteBuffer[] buffers = new ByteBuffer[0];
int bidx, pos, length;
@Override
public int read(byte[] b, int off, int len) {
if (bidx >= buffers.length) {
return -1;
}
int cur = 0;
do {
int rem = Math.min(len, buffers[bidx].remaining());
buffers[bidx].get(b, off, rem);
cur += rem;
off += rem;
len -= rem;
} while (len > 0 && ++bidx < buffers.length); //bidx is unsynchronized
pos += cur;
return cur;
}
public void reset(ByteBuffer[] buffers) {//if one thread keeps calling reset() in a loop
bidx = pos = length = 0;
this.buffers = buffers;
for (ByteBuffer b : buffers) {
length += b.remaining();
}
}