SEPURI-SAI-KRISHNA commented on code in PR #22755:
URL: https://github.com/apache/kafka/pull/22755#discussion_r3629601322
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clients/src/main/java/org/apache/kafka/common/serialization/ListDeserializer.java:
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@@ -196,7 +195,12 @@ public List<Inner> deserialize(String topic, Headers
headers, byte[] data) {
continue;
}
byte[] payload = new byte[entrySize];
- if (dis.read(payload) == -1) {
+ try {
+ // Use readFully (not read) so a stream truncated
mid-entry is detected: read(byte[]) may
+ // return a partial count without reaching EOF, which
would silently leave the tail of the
+ // payload zero-filled and hand a corrupted entry to the
inner deserializer.
+ dis.readFully(payload);
+ } catch (EOFException e) {
Review Comment:
@mjsax Good call-out I did weigh that. The reason I went with readFully is a
corner case where read() != entrySize over-rejects: when the list's last
element serializes to zero bytes (e.g. a trailing empty, non-null String), the
final entrySize is 0 and the stream is already at EOF.
ByteArrayInputStream.read(new byte[0]) returns -1 at EOF rather than 0, so
read(payload) != entrySize becomes -1 != 0 and throws on a valid list.
readFully(new byte[0]) performs no read and returns normally.
new DataInputStream(new ByteArrayInputStream(new byte[0])).read(new
byte[0]); // -> -1, not 0
The current read() == -1 has the same issue, so readFully also fixes
deserializing a list whose last entry is empty. I've added
shouldDeserializeListEndingInEmptyEntry to cover it. The EOFException is caught
locally and mapped straight to the existing SerializationException, so it
doesn't leak beyond this block — but if you'd still prefer to avoid the
exception, I can special-case entrySize == 0 alongside the length check.
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