Bug #11909 mysql_stmt_attr_set CURSOR_TYPE_READ_ONLY nested queries corrupt result
Submitted: 13 Jul 2005 13:24 Modified: 14 Aug 2005 2:39
Reporter: Berto van de Kraats
Status: Closed
Category:Server Severity:S1 (Critical)
Version:5.0.10-beta OS:Linux (Linux)
Assigned to: Konstantin Osipov Target Version:

[13 Jul 2005 13:24] Berto van de Kraats 
Description:
If cursors are enabled, and queries on the same table are nested then the outer query
returns corrupt data.

How to repeat:
Compile and run the attached program (which is an automatically generated trace of our
mysql database driver). The problem reproduces if the program silently runs and has exit
status 0.

The trace contains a call to mysql_stmt_fetch that returns corrupted data (search for
pattern "ERROR:" in attached program).
[13 Jul 2005 13:25] Berto van de Kraats 
Cpp trace of problem

Attachment: bug11909.cpp (text/plain), 29.68 KiB.
[13 Jul 2005 14:00] Berto van de Kraats 
Another cpp trace of the problem

Attachment: bug11902.cpp (text/plain), 26.92 KiB.
[13 Jul 2005 20:11] Jorge del Conde 
Thanks for your excellent bug report Peter.  I was able to reproduce this bug using
5.0.10bk.
[22 Jul 2005 20:04] Andrey Hristov 
there is off-by-1 problem. the problem is that the pointer in the row advances one
position more than needed and then the beginning of a text string is read as it's length
and then the data is corrupted. when run in debugger and manually move the pointer with 1
byte behind everything is fine. I will continue investigating where exactly the problem is
created.
[22 Jul 2005 20:05] Andrey Hristov 
assigning to me
[3 Aug 2005 20:19] Bugs System 
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/internals/27856
[8 Aug 2005 17:05] Bugs System 
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/internals/28000
[8 Aug 2005 17:32] Konstantin Osipov 
Pushed into 5.0 tree, tagged 5.0.12
[14 Aug 2005 2:39] Paul DuBois 
Noted in 5.0.12 changelog.