BASH PATCH REPORT

			     =================

Bash-Release:	4.4

Patch-ID:	bash44-009

Bug-Reported-by:	Hong Cho <[email protected]>

Bug-Reference-ID:	<[email protected]>

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_ */