Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-5181

incorrect binary search in remove_status_vars()

Details

    • Bug
    • Status: Closed (View Workflow)
    • Critical
    • Resolution: Fixed
    • 10.0.4, 5.5.33a
    • 5.5.34, 10.0.6
    • None

    Description

      On INSTALL SONAME 'ha_tokudb.so' when TokuDB cannot be installed (for example, because transparent hugepages are enabled), MariaDB hangs.

      The reason is the remove_status_vars() function that has incorrectly implemented binary search to remove plugin variables from the all-variables list. The code

            for (; b-a > 0; c= (a+b)/2)
      		 
            {
      		 
              res= show_var_cmp(list, all+c);
      		 
              if (res < 0)
      		 
                b= c;
      		 
              else if (res > 0)
      		 
                a= c;
      		 
              else
      		 
                break;
      		 
            }

      in my test, a=129, b=130. So, c=129, in comparison I get res > 0, and the loop continues till infinity.

      Attachments

        Activity

          Ascending order - Click to sort in descending order
          pomyk Patryk Pomykalski added a comment - - edited

          I came up with something like this:

          — sql/sql_show.cc 2013-07-16 17:09:54 +0000
          +++ sql/sql_show.cc 2013-11-05 21:59:41 +0000
          @@ -2550,17 +2550,18 @@

          for (; list->name; list++)
          {

          • int res= 0, a= 0, b= all_status_vars.elements, c= (a+b)/2;
          • for (; b-a > 0; c= (a+b)/2)
            + int res= 0, a= 0, b= all_status_vars.elements, c;
            + do { + c= (a+b)/2; res= show_var_cmp(list, all+c); if (res < 0) - b= c; + b= c - 1; else if (res > 0) - a= c; + a= c + 1; else break; - }

            + } while (b >= a && a < all_status_vars.elements);
            if (res == 0)
            all[c].type= SHOW_UNDEF;
            }

          pomyk Patryk Pomykalski added a comment - - edited I came up with something like this: — sql/sql_show.cc 2013-07-16 17:09:54 +0000 +++ sql/sql_show.cc 2013-11-05 21:59:41 +0000 @@ -2550,17 +2550,18 @@ for (; list->name; list++) { int res= 0, a= 0, b= all_status_vars.elements, c= (a+b)/2; for (; b-a > 0; c= (a+b)/2) + int res= 0, a= 0, b= all_status_vars.elements, c; + do { + c= (a+b)/2; res= show_var_cmp(list, all+c); if (res < 0) - b= c; + b= c - 1; else if (res > 0) - a= c; + a= c + 1; else break; - } + } while (b >= a && a < all_status_vars.elements); if (res == 0) all [c] .type= SHOW_UNDEF; }
          bar Alexander Barkov added a comment -

          Pushed into 5.1, 5.2, 5.3, 5.5, 10.0-base.

          bar Alexander Barkov added a comment - Pushed into 5.1, 5.2, 5.3, 5.5, 10.0-base.

          People

            bar Alexander Barkov
            serg Sergei Golubchik
            Votes:
            1 Vote for this issue
            Watchers:
            5 Start watching this issue

            Dates

              Created:
              Updated:
              Resolved:

              Git Integration

                Error rendering 'com.xiplink.jira.git.jira_git_plugin:git-issue-webpanel'. Please contact your Jira administrators.