Yiyuan GUO created HADOOP-17711:
-----------------------------------
Summary: A divide by zero bug in
LoadBalancingKMSClientProvider.java
Key: HADOOP-17711
URL: https://issues.apache.org/jira/browse/HADOOP-17711
Project: Hadoop Common
Issue Type: Bug
Components: kms
Affects Versions: 3.2.2
Reporter: Yiyuan GUO
In the file _kms/LoadBalancingKMSClientProvider.java_, the function
_rollNewVersion_ has the following
[code|https://github.com/apache/hadoop/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/crypto/key/kms/LoadBalancingKMSClientProvider.java#L509-#L516]:
{code:java}
@Override
public KeyVersion rollNewVersion(final String name, final byte[] material)
throws IOException {
final KeyVersion newVersion = doOp(new ProviderCallable<KeyVersion>() {
@Override
public KeyVersion call(KMSClientProvider provider) throws IOException {
return provider.rollNewVersion(name, material);
}
}, nextIdx(), false);
...
}
{code}
The function _nextIdx_ uses _providers.length_ as a __ divisor:
{code:java}
private int nextIdx() {
while (true) {
int current = currentIdx.get();
int next = (current + 1) % providers.length;
......
}{code}
However, _providers.length_ may be equal to zero, since the function _doOp_
explicitly checks that and throws an exception when it happens:
{code:java}
private <T> T doOp(ProviderCallable<T> op, int currPos,
boolean isIdempotent) throws IOException {
if (providers.length == 0) {
throw new IOException("No providers configured !");
}
...
}
{code}
The problem is that when _providers.length_ is 0, a divide by zero problem will
happen when computing the argument for _doOp_ (inside the function _nextIdx_)
__ before reaching the protection check above, causing an ArithmeticException.
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