Re: [MLB] Linux fails test 'mdemo-exec.test' with Segmentation fault!

[Robert Boehne]

OK, the patch just creates an infinite loop rather than
fixing the problem.  Anyone else know how to fix this?

Robert


Robert Boehne wrote:
> 
> On Linux (Redhat 6.2) one of the test cases
> (the second execution of mdemo-exec.test) is failing with
> the current CVS version of libtool.  The problems is a segmentation
> fault coming from ltdl.c in the function lt_dlexit.  The following
> debugging session shows that when on line 1117, the pointer 'cur'
> is incremented to the next structure, it's value becomes 0, then
> it is accessed in LT_DLIS_RESIDENT (cur), which results in
> a segmentation fault.
>   I assume that all that needs to be done to fix this is to add a check
> for a zero value after the 'cur = cur->next' statement.  Attached is
> a patch that does just that.  Here is a ChangeLog entry:
> 
> 2000-12-18  Robert Boehne  <address@hidden>
> 
>         * libltdl/ltdl.c (lt_dlexit): Test for a null value in 'cur'
>         before accessing it.
> 
> This patch fixes the error, but as I'm not familiar with the code in
> libltdl, I would like someone who is to really examine this.
> 
> Thanks,
> 
> Robert
> 
> icarus::/boreas/libtool/tests (154)% gdb ../mdemo/mdemo
> GNU gdb 5.0
> Copyright 2000 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you
> are
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> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for
> details.
> This GDB was configured as "i386-redhat-linux"...Warning:
> /tmp_mnt/boreas/libtool/tests/@: No such file or directory.
> 
> (gdb) run ../mdemo/foo1.la ../mdemo/libfoo2.la
> Starting program: /tmp_mnt/boreas/libtool/tests/../mdemo/mdemo
> ../mdemo/foo1.la ../mdemo/libfoo2.la
> Welcome to GNU libtool mdemo!
> ** This is foolib 1 **
> hello returned: 57616
> hello is ok!
> cos (0.0) = 1
> foo1 is ok!
> ** This is foolib 2 **
> hello returned: 57616
> hello is ok!
> sin (0.0) = 0
> foo2 is ok!
> myfunc returned: 57616
> myfunc is ok!
> 
> Program received signal SIGSEGV, Segmentation fault.
> lt_dlexit () at ltdl.c:1118
> 1118                  if (!LT_DLIS_RESIDENT (cur) && tmp->info.ref_count <= 
> level)
> (gdb) where
> #0  lt_dlexit () at ltdl.c:1118
> #1  0x80492bf in main (argc=3, argv=0xbffff734) at main.c:173
> #2  0x400379cb in __libc_start_main (main=0x8049218 <main>, argc=3,
> argv=0xbffff734, init=0x8048d24 <_init>, fini=0x804b87c <_fini>,
> rtld_fini=0x4000ae60 <_dl_fini>, stack_end=0xbffff72c)
>     at ../sysdeps/generic/libc-start.c:92
> (gdb) print cur
> $1 = 0x0
> (gdb) print tmp
> $2 = 0x804d278
> (gdb) print tmp->next
> $3 = (struct lt_dlhandle_struct *) 0x0
> (gdb) print handles
> $4 = 0x804d278
> (gdb) print initialized
> $5 = 0
> 
> --
> Robert Boehne             Software Engineer
> Ricardo Software   Chicago Technical Center
> TEL: (630)789-0003 x. 238
> FAX: (630)789-0127
> email:  address@hidden
> 
>   ------------------------------------------------------------------------
> Index: ltdl.c
> ===================================================================
> RCS file: /home/cvs/libtool/libltdl/ltdl.c,v
> retrieving revision 1.82.2.11
> diff -u -r1.82.2.11 ltdl.c
> --- ltdl.c      2000/12/16 03:19:09     1.82.2.11
> +++ ltdl.c      2000/12/18 20:29:32
> @@ -1115,7 +1115,7 @@
>             {
>               lt_dlhandle tmp = cur;
>               cur = cur->next;
> -             if (!LT_DLIS_RESIDENT (cur) && tmp->info.ref_count <= level)
> +             if (cur && !LT_DLIS_RESIDENT (cur) && tmp->info.ref_count <= 
> level)
>                 {
>                   if (lt_dlclose (tmp))
>                     {

-- 
Robert Boehne             Software Engineer
Ricardo Software   Chicago Technical Center
TEL: (630)789-0003 x. 238
FAX: (630)789-0127
email:  address@hidden