Bug #47130 misplaced or redundant check for null pointer ?

• Submitted: 4 Sep 2009 10:49
• Modified: 18 Dec 2009 23:52
• Reporter: Shane Bester (Platinum Quality Contributor)
• Status: Closed
• Category: MySQL Server: General
• Severity: S3 (Non-critical)
• Version: 5.1.39
• OS: Any
• Assigned to: Ramil Kalimullin
• CPU Architecture: Any

[4 Sep 2009 10:49] Shane Bester

Description:
in ./sql/log.cc we have;

bool LOGGER::general_log_write(THD *thd, enum enum_server_command command,
                               const char *query, uint query_length)
{
...
 Security_context *sctx= thd->security_ctx;
...
if (thd)
    id= thd->thread_id;                 /* Normal thread */
 else
    id= 0;                              /* Log from connect handler */
...
}

if thd was null, it would have segfaulted before the check.
the rest of the function goes on to assume thd is never null, this is why
this looks wrongly handled.

How to repeat:
review the code

Suggested fix:
cleanup the code.

[11 Sep 2009 17:07] 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/commits/83077

3120 Ramil Kalimullin	2009-09-11
      Fix for bug#47130: misplaced or redundant check for null pointer?
      
      Problem: LOGGER::general_log_write() relied on valid "thd" parameter passed
      but had inconsistent "if (thd)" check.
      
      Fix: as we always pass a valid "thd" parameter to the method, 
      redundant check removed.
     @ sql/log.cc
        Fix for bug#47130: misplaced or redundant check for null pointer?
          - code clean-up, as we rely on the "thd" parameter in the
        LOGGER::general_log_write(), redundant "if (thd)" check removed, 
        added assert(thd) instead.

[14 Sep 2009 16:03] Bugs System

Pushed into 5.4.4-alpha (revid:[e-mail]-20090914155317-m1g9wodmndzdj4l1) (version source revid:[e-mail]-20090914155317-m1g9wodmndzdj4l1) (merge vers: 5.4.4-alpha) (pib:11)

[6 Oct 2009 9:01] Bugs System

Pushed into 5.1.40 (revid:[e-mail]-20091006073316-lea2cpijh9r6on7c) (version source revid:[e-mail]-20090916070128-6053el2ucp5z7pyn) (merge vers: 5.1.39) (pib:11)

[7 Oct 2009 0:49] Paul DuBois

Code cleanup. No changelog entry required.

[18 Dec 2009 10:28] Bugs System

Pushed into 5.1.41-ndb-7.1.0 (revid:[e-mail]-20091218102229-64tk47xonu3dv6r6) (version source revid:[e-mail]-20091218095730-26gwjidfsdw45dto) (merge vers: 5.1.41-ndb-7.1.0) (pib:15)

[18 Dec 2009 10:44] Bugs System

Pushed into 5.1.41-ndb-6.2.19 (revid:[e-mail]-20091218100224-vtzr0fahhsuhjsmt) (version source revid:[e-mail]-20091217101452-qwzyaig50w74xmye) (merge vers: 5.1.41-ndb-6.2.19) (pib:15)

[18 Dec 2009 10:59] Bugs System

Pushed into 5.1.41-ndb-6.3.31 (revid:[e-mail]-20091218100616-75d9tek96o6ob6k0) (version source revid:[e-mail]-20091217154335-290no45qdins5bwo) (merge vers: 5.1.41-ndb-6.3.31) (pib:15)

[18 Dec 2009 11:13] Bugs System

Pushed into 5.1.41-ndb-7.0.11 (revid:[e-mail]-20091218101303-ga32mrnr15jsa606) (version source revid:[e-mail]-20091218064304-ezreonykd9f4kelk) (merge vers: 5.1.41-ndb-7.0.11) (pib:15)