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  1. Cassandra
  2. CASSANDRA-14284

Chunk checksum test needs to occur before uncompress to avoid JVM crash

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    • Severity:
      Normal

      Description

      While checksums are (generally) performed on compressed data, the checksum test when reading is currently (in all variants of C* 2.x, 3.x I've looked at) done [on the compressed data] only after the uncompress operation has completed. 

      The issue here is that LZ4_decompress_fast (as documented in e.g. https://github.com/lz4/lz4/blob/dev/lib/lz4.h#L214) can result in memory overruns when provided with malformed source data. This in turn can (and does, e.g. in CASSANDRA-13757) lead to JVM crashes during the uncompress of corrupted chunks. The checksum operation would obviously detect the issue, but we'd never get to it if the JVM crashes first.

      Moving the checksum test of the compressed data to before the uncompress operation (in cases where the checksum is done on compressed data) will resolve this issue.

      -----------------------------

      The check-only-after-doing-the-decompress logic appears to be in all current releases.

      Here are some samples at different evolution points :

      3.11.2:

      https://github.com/apache/cassandra/blob/cassandra-3.11.2/src/java/org/apache/cassandra/io/util/CompressedChunkReader.java#L146

      https://github.com/apache/cassandra/blob/cassandra-3.11.2/src/java/org/apache/cassandra/io/util/CompressedChunkReader.java#L207

       

      3.5:

       https://github.com/apache/cassandra/blob/cassandra-3.5/src/java/org/apache/cassandra/io/compress/CompressedRandomAccessReader.java#L135

      https://github.com/apache/cassandra/blob/cassandra-3.5/src/java/org/apache/cassandra/io/compress/CompressedRandomAccessReader.java#L196

      2.1.17:

       https://github.com/apache/cassandra/blob/cassandra-2.1.17/src/java/org/apache/cassandra/io/compress/CompressedRandomAccessReader.java#L122

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              • Assignee:
                blerer Benjamin Lerer
                Reporter:
                giltene Gil Tene
                Authors:
                Benjamin Lerer
                Reviewers:
                Branimir Lambov
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                • Created:
                  Updated:
                  Resolved: