Re: [PATCH] solib-svr4.c, several memory leaks

[msnyder@sonic.net]

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Jim, Kevin,

Apparently we can't free the tmp name while bfd has the file open.
Moving the xfree to later, after it has been closed, seems to fix
the segfault.

See attached patch.
Michael

> Folks,
>
> GDB started acting strange today, segfaulting when trying to open some
> binaries, GDB itself included. Other binaries would work OK.
>
> Log:
>
> -------
> ~/builds/gdb-head/> gdb-head-64bit/gdb/gdb gdb-head-64bit/gdb/gdb
> GNU gdb 6.6.50.20070809-cvs
> Copyright (C) 2007 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you
> are
> welcome to change it and/or distribute copies of it under certain
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for
> details.
> This GDB was configured as "powerpc64-unknown-linux-gnu"...
> startUsing host libthread_db library "/lib64/ppc970/libthread_db.so.1".
> (gdb) start
> Breakpoint 1 at 0x10060b3c: file gdb-head/gdb/gdb.c, line 30.
> Starting program: gdb-head-64bit/gdb/gdb
> BFD: reopening : No such file or directory
>
> Segmentation fault
> -------
>
>
> I tracked down the root of the problem and this patch appears to be the
> problem. Reverting it back fixes the problem.


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Index: solib-svr4.c
===================================================================
RCS file: /cvs/src/src/gdb/solib-svr4.c,v
retrieving revision 1.72
diff -p -r1.72 solib-svr4.c
*** solib-svr4.c	8 Aug 2007 18:08:52 -0000	1.72
--- solib-svr4.c	10 Aug 2007 00:09:19 -0000
*************** enable_break (void)
*** 1008,1014 ****
        tmp_fd = solib_open (buf, &tmp_pathname);
        if (tmp_fd >= 0)
  	tmp_bfd = bfd_fopen (tmp_pathname, gnutarget, FOPEN_RB, tmp_fd);
-       xfree (tmp_pathname);
  
        if (tmp_bfd == NULL)
  	goto bkpt_at_symbol;
--- 1008,1013 ----
*************** enable_break (void)
*** 1102,1107 ****
--- 1101,1107 ----
        /* For whatever reason we couldn't set a breakpoint in the dynamic
           linker.  Warn and drop into the old code.  */
      bkpt_at_symbol:
+       xfree (tmp_pathname);
        warning (_("Unable to find dynamic linker breakpoint function.\n"
                 "GDB will be unable to debug shared library initializers\n"
                 "and track explicitly loaded dynamic code."));