Re: [patch] Fix ELF stale reference

[Jan Kratochvil <jan.kratochvil@redhat.com>]

On Thu, 14 Oct 2010 19:46:13 +0200, Tom Tromey wrote:
> >>>>> "Jan" == Jan Kratochvil <jan.kratochvil@redhat.com> writes:
> 
> Jan> OK to check-in?  Or some bfd/ API improvement should be made?
> 
> I think this is probably the cleanest fix.

Checked in.


> However, libbfd.h does say right at the top that it shouldn't be used.
> 
> I guess we could ask for advice on the binutils list.

This part has been fixed recently in binutils (as you forwarded me):
	http://sourceware.org/ml/binutils/2010-10/msg00413.html

So no new libbfd.h include is now needed in GDB.


Regarding the introduced memory leak it seems to be fixable but I have only
filed GDB PR for it now:
	http://sourceware.org/bugzilla/show_bug.cgi?id=12243


Thanks,
Jan


http://sourceware.org/ml/gdb-cvs/2010-11/msg00094.html

--- src/gdb/ChangeLog	2010/11/19 18:10:43	1.12319
+++ src/gdb/ChangeLog	2010/11/19 22:30:44	1.12320
@@ -1,4 +1,10 @@
 2010-11-19  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	Fix stale memory references.
+	* elfread.c (elf_symfile_read): Replace xmalloc by bfd_alloc, drop
+	xfree, new comment.
+
+2010-11-19  Jan Kratochvil  <jan.kratochvil@redhat.com>
 	    Tom Tromey  <tromey@redhat.com>
 
 	* Makefile.in (.y.c): Directly create $@ from YLWRAP.
--- src/gdb/elfread.c	2010/10/01 20:26:11	1.99
+++ src/gdb/elfread.c	2010/11/19 22:30:47	1.100
@@ -790,8 +790,14 @@
 
   if (storage_needed > 0)
     {
-      dyn_symbol_table = (asymbol **) xmalloc (storage_needed);
-      make_cleanup (xfree, dyn_symbol_table);
+      /* Memory gets permanently referenced from ABFD after
+	 bfd_get_synthetic_symtab so it must not get freed before ABFD gets.
+	 It happens only in the case when elf_slurp_reloc_table sees
+	 asection->relocation NULL.  Determining which section is asection is
+	 done by _bfd_elf_get_synthetic_symtab which is all a bfd
+	 implementation detail, though.  */
+
+      dyn_symbol_table = bfd_alloc (abfd, storage_needed);
       dynsymcount = bfd_canonicalize_dynamic_symtab (objfile->obfd,
 						     dyn_symbol_table);