[KUDU-2085] Seek past last element of a prefix-encoded binary block may crash

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 1.0.1, 1.1.0, 1.2.0, 1.3.1, 1.4.0
• Fix Version/s: 1.3.2, 1.5.0, 1.2.1, 1.4.1
• Component/s: cfile
• Target Version/s: 1.3.2, 1.5.0, 1.2.1, 1.4.1
• Code Review: https://gerrit.cloudera.org/#/c/7545/
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 31/Jul/17 21:24
• Updated: 05/Sep/17 20:24
• Resolved: 08/Aug/17 17:36

Description

Similar to KUDU-2049, the binary prefix block encoder has a bug when seeking past the end of the block (i.e to the offset past the last element). The bug only causes issues in very specific circumstances:

• the number of elements in the block has to be a multiple of 16 (the "restart interval")
  • this causes the code to interpret the "restart count" at the end of the block data as an offset instead of part of the footer.
• this value, when interpreted as an offset, points to a piece of data in the block which, when interpreted as a varint, ends up large enough to point past the end of the block.

This results in an error like:
F0730 09:56:07.291882 124055 binary_prefix_block.cc:325] Check failed: _s.ok() Bad status: Corruption: Could not decode value length data at idx 32