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From:Round Square Date:December 27 2012 10:34am
Subject:Re: Automatic reply: "access denied" to non-root@localhost &
null-string user in USER_PRIVILEGES
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On 12/26/2012 01:25 PM, Igor Shevtsov wrote:
> You mysql.user table might be corrupted.
> If you have access to it as a root user, try check table mysql.user, and repair table
> mysql.user if table corruption was detected.
> Alternatively, shut down mysql server, cd /var/lib/mysql/mysql (to your
> $datadir/mysql directory) and run
> mysqlcheck -r mysql user

I deleted the row with the empty user from mysql.user, then restarted the daemon, and all
seems back to normal now.

One lingering question is:  why did mysql allow this to happen?  Could this be considered
a bug?  After all, an inadvertent and seemingly harmless insertion leads to authentication
failure for all users.

Are there any other known similar gotchas?  The fix for this one appears so trivial as to
perhaps NOT call for a restore-from-backup.  But there could be other similar glitches
that might call for that?


> On 26/12/12 18:00, Round Square wrote:
>> Hi all:
>>   Suddenly, after a long, functioning run of the mysql server, all the non-root
> accounts went bad, with:
>>             Access denied for user 'non_root_user'@'localhost' (using password:
> YES)
>> Authenticating with "non_root_user@stripped" still works ( the
> bind-address in my.cnf is mapped to server.ip.address )
>> Poking around in puzzlement and comparing the current, broken state with the
> functioning state (from backup) I discovered that in the broken version there is this
> extra line in the information_schema.USER_PRIVILEGES table:
>>            | ''@'localhost'                 | NULL          | USAGE              
>     | NO           |
>> (Note the null-string user prepended to "@localhost")
>> Again: the functional, non-broken state does NOT have this entry.  Thus, my
> current theory is that this line is the culprit.  Prior to the failure I had a surge of
> experimental installations, installing third-party software that created mysql tables, and
> can't clearly retrace everything I did, at this point, to pinpoint the installation that
> may have caused it.
>> Be that as it may...
>> (1) Is my theory correct?
>> (2) If that line should not be there...
>>         (a) How do I remove it, properly? I don't have debian-sys-maint
> privileges to delete the line. (Or do I?)
>>         (b) Are there other tables, besides USER_PRIVILEGES, that would need to
> be updated/purged
>> My version:
>> mysql  Ver 14.14 Distrib 5.1.41, for debian-linux-gnu (i486) using readline 6.1
Re: Automatic reply: "access denied" to non-root@localhost &null-string user in USER_PRIVILEGESRound Square27 Dec
  • Re: Automatic reply: "access denied" to non-root@localhost & null-stringuser in USER_PRIVILEGESShawn Green3 Jan