Re: gdb crash: double free with free_objfile

[Mathieu Lacage <mathieu.lacage@gmail.com>]

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hi,

On Fri, Feb 5, 2010 at 5:39 PM, Tom Tromey <tromey@redhat.com> wrote:

> Nope, right now objfile has the base address baked in to many things,
> e.g. symbol addresses or psymtabs_addrmap.  I think we'd like to change
> this, so that we can share objfiles between inferiors, but nobody has
> tried to do that yet.  I don't know how hard this would be.
>
> Your quickest route is probably a form of (a) -- change symbol_add_stub
> to check both the file name and the base address.

It took me a long time to get back to this issue because I was busy
with a couple of other things but the attached patch which was
generated against CVS HEAD fixes the problem for me (i.e., avoids the
segfault in gdb and gets me readable backtraces). Is there something
else I could do to help get this issue fixed in mainline ?

Mathieu
-- 
Mathieu Lacage <mathieu.lacage@gmail.com>

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? objdir
? solib.patch
Index: gdb/objfiles.h
===================================================================
RCS file: /cvs/src/src/gdb/objfiles.h,v
retrieving revision 1.72
diff -u -r1.72 objfiles.h
--- gdb/objfiles.h	14 Apr 2010 17:26:11 -0000	1.72
+++ gdb/objfiles.h	23 Jun 2010 15:14:16 -0000
@@ -193,6 +193,8 @@
 
     char *name;
 
+    CORE_ADDR addr_low;
+
     /* Some flag bits for this objfile. */
 
     unsigned short flags;
Index: gdb/solib.c
===================================================================
RCS file: /cvs/src/src/gdb/solib.c,v
retrieving revision 1.140
diff -u -r1.140 solib.c
--- gdb/solib.c	16 May 2010 23:49:58 -0000	1.140
+++ gdb/solib.c	23 Jun 2010 15:14:16 -0000
@@ -634,11 +634,11 @@
       TRY_CATCH (e, RETURN_MASK_ERROR)
 	{
 	  struct section_addr_info *sap;
-
 	  /* Have we already loaded this shared object?  */
 	  ALL_OBJFILES (so->objfile)
 	    {
-	      if (strcmp (so->objfile->name, so->so_name) == 0)
+	      if (strcmp (so->objfile->name, so->so_name) == 0
+		  && so->objfile->addr_low == so->addr_low)
 		break;
 	    }
 	  if (so->objfile != NULL)
@@ -648,6 +648,7 @@
 							    so->sections_end);
 	  so->objfile = symbol_file_add_from_bfd (so->abfd,
 						  flags, sap, OBJF_SHARED);
+	  so->objfile->addr_low = so->addr_low;
 	  free_section_addr_info (sap);
 	}