MySQL Bugs: #27018: Partial blob write inside blob clobbers data after the write

Bug #27018	Partial blob write inside blob clobbers data after the write
Submitted:	9 Mar 2007 23:27	Modified:	10 Apr 2007 15:01
Reporter:	Kristian Nielsen
Status:	Closed
Category:	Server: NDBAPI	Severity:	S3 (Non-critical)
Version:	5.0.38, 5.1.17	OS:	Any
Assigned to:	Kristian Nielsen	Target Version:

Description:
Using NdbBlob::writeData() to write data in the middle of an existing blob
value (update) may overwrite some data after the end of the writeData().

The problem is that the code wrongly zero-pads the blob (or space-pads the
text field) up to the end of the part, overwriting existing data.

How to repeat:
I will commit a patch with attached test case added for testBlobs.

Suggested fix:
Will commit patch.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/21662

ChangeSet@1.2447, 2007-03-09 23:37:33+01:00, knielsen@ymer.(none) +2 -0
  BUG#27018: Partial blob write inside blob clobbers data after the write.
  
  When doing partial blob update with NdbBlob::writeData(), zero-padding
  after the write was wrongly done, causing part of the old blob value
  to be overwritten with zeros (or spaces for text field).
  
  Fixed by only padding when needed (when writing at end of the blob).

Pushed to mysql-5.0-ndb and mysql-5.1-new-ndb.

5.0.40, 5.1.18, telco 6.2.1

Thank you for your bug report. This issue has been committed to our source repository of
that product and will be incorporated into the next release.

If necessary, you can access the source repository and build the latest available version,
including the bug fix. More information about accessing the source trees is available at

    http://dev.mysql.com/doc/en/installing-source.html

Documented bugfix in 5.0.40, 5.1.18, and telco-6.2.1 changelogs.