Re: Bash crashes with segfault on certain script constructs

[Chet Ramey]

>   Machine Type: i686-pc-linux-gnu
>   
>   Bash Version: 3.0
>   Patch Level: 0
>   Release Status: release
>   
>   Description:
>       Bash crashes on Execution of FireHOL 196, which is a shell script.
>       No shell script should be able to crash a shell.
>   
>   Repeat-By:
>   
>       The following script triggers the segfault.
>       This was found by Costa Tsaousis the author of FireHOL.
>         He wrotes:
> 
>         "I think I have found the bug. The script bellow crashes at the
>        third echo (UNSET). It seems to be a problem of the "unset" BASH
>        function when erasing arrays. It leaves something behind so that if
>        the array just unset is referenced, it produces a segmentation fault.
>        According to the documentation the first and the third expansions
>        should be exactly the same."
>  
>       -----------------------------------------------------------
>       !/bin/sh
>       rule() {
>                   echo "1. BEFORE SET:" "${s[@]}"
>   
>                   local -a s=()
>                   echo "2. SET TO EMPTY:" "${s[@]}"
>                   unset s
>                   echo "3. UNSET:" "${s[@]}"
>       }
>   
>       rule

Try this patch.

*** ../bash-3.0/arrayfunc.c     Fri Dec 19 00:03:09 2003
--- arrayfunc.c Sun Aug  1 20:43:00 2004
***************
*** 612,616 ****
  
    free (t);
!   return var;
  }
  
--- 612,616 ----
  
    free (t);
!   return (var == 0 || invisible_p (var)) ? (SHELL_VAR *)0 : var;
  }
  

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
( ``Discere est Dolere'' -- chet )
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Chet Ramey, ITS, CWRU    chet@po.cwru.edu    http://tiswww.tis.cwru.edu/~chet/