Bug #59959 small values of --max-allowed-packet are not being honored
Submitted: 5 Feb 2011 0:51 Modified: 26 Apr 2011 15:20
Reporter: Shawn Green Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: General Severity:S2 (Serious)
Version:5.1.49 OS:Any
Assigned to: CPU Architecture:Any

[5 Feb 2011 0:51] Shawn Green 
Description:
The MySQL command line client can send commands larger than the max_allowed_packet value and they are not being rejected. 

The test case below clearly shows that the max_allowed_packet value was set and that I was able to execute a command much larger than the indicated value. 

max_allowed_packet is a protective setting. If it is failing, then this could be serious. 

How to repeat:
Too large to post in this field. See attached test case.

Suggested fix:
Respect the max_allowed_packet limit or update the manual to indicate when it is ignored.
[5 Feb 2011 0:52] MySQL Verification Team 
A session log indicating the failure of max_allowed_packet to reject a command that was too large

Attachment: bug59959_testcase.txt (text/plain), 11.76 KiB.
[26 Apr 2011 15:20] Paul DuBois 
Noted in 5.1.57, 5.5.12, 5.6.3 changelogs.

The server permitted max_allowed_packet to be set lower than 
net_buffer_length, which does not make sense because
max_allowed_packet is the upper limit on net_buffer_length values.
Now a warning occurs and the value remains unchanged. 

CHANGESET - http://lists.mysql.com/commits/134032