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Bash-4.4 Official Patch 9


From: Chet Ramey
Subject: Bash-4.4 Official Patch 9
Date: Fri, 20 Jan 2017 15:18:50 -0500

                             BASH PATCH REPORT
                             =================

Bash-Release:   4.4
Patch-ID:       bash44-009

Bug-Reported-by:        Hong Cho <address@hidden>
Bug-Reference-ID:       <address@hidden>
Bug-Reference-URL:      
http://lists.gnu.org/archive/html/bug-bash/2016-12/msg00043.html

Bug-Description:

There is a race condition in add_history() that can be triggered by a fatal
signal arriving between the time the history length is updated and the time
the history list update is completed. A later attempt to reference an
invalid history entry can cause a crash.

Patch (apply with `patch -p0'):

*** ../bash-4.4-patched/lib/readline/history.c  2016-11-11 13:42:49.000000000 
-0500
--- lib/readline/history.c      2016-12-05 10:37:51.000000000 -0500
***************
*** 280,283 ****
--- 280,284 ----
  {
    HIST_ENTRY *temp;
+   int new_length;
  
    if (history_stifled && (history_length == history_max_entries))
***************
*** 296,306 ****
        /* Copy the rest of the entries, moving down one slot.  Copy includes
         trailing NULL.  */
- #if 0
-       for (i = 0; i < history_length; i++)
-       the_history[i] = the_history[i + 1];
- #else
        memmove (the_history, the_history + 1, history_length * sizeof 
(HIST_ENTRY *));
- #endif
  
        history_base++;
      }
--- 297,303 ----
        /* Copy the rest of the entries, moving down one slot.  Copy includes
         trailing NULL.  */
        memmove (the_history, the_history + 1, history_length * sizeof 
(HIST_ENTRY *));
  
+       new_length = history_length;
        history_base++;
      }
***************
*** 316,320 ****
            history_size = DEFAULT_HISTORY_INITIAL_SIZE;
          the_history = (HIST_ENTRY **)xmalloc (history_size * sizeof 
(HIST_ENTRY *));
!         history_length = 1;
        }
        else
--- 313,317 ----
            history_size = DEFAULT_HISTORY_INITIAL_SIZE;
          the_history = (HIST_ENTRY **)xmalloc (history_size * sizeof 
(HIST_ENTRY *));
!         new_length = 1;
        }
        else
***************
*** 326,330 ****
                xrealloc (the_history, history_size * sizeof (HIST_ENTRY *));
            }
!         history_length++;
        }
      }
--- 323,327 ----
                xrealloc (the_history, history_size * sizeof (HIST_ENTRY *));
            }
!         new_length = history_length + 1;
        }
      }
***************
*** 332,337 ****
    temp = alloc_history_entry ((char *)string, hist_inittime ());
  
!   the_history[history_length] = (HIST_ENTRY *)NULL;
!   the_history[history_length - 1] = temp;
  }
  
--- 329,335 ----
    temp = alloc_history_entry ((char *)string, hist_inittime ());
  
!   the_history[new_length] = (HIST_ENTRY *)NULL;
!   the_history[new_length - 1] = temp;
!   history_length = new_length;
  }
  
*** ../bash-4.4/patchlevel.h    2016-06-22 14:51:03.000000000 -0400
--- patchlevel.h        2016-10-01 11:01:28.000000000 -0400
***************
*** 26,30 ****
     looks for to find the patch level (for the sccs version string). */
  
! #define PATCHLEVEL 8
  
  #endif /* _PATCHLEVEL_H_ */
--- 26,30 ----
     looks for to find the patch level (for the sccs version string). */
  
! #define PATCHLEVEL 9
  
  #endif /* _PATCHLEVEL_H_ */

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    address@hidden    http://cnswww.cns.cwru.edu/~chet/



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