Use gdb_bfd_ref_ptr in objfile

This changes struct objfile to use a gdb_bfd_ref_ptr.  In addition to
removing some manual memory management, this fixes a use-after-free
that was introduced by the registry rewrite series.  The issue there
was that, in some cases, registry shutdown could refer to memory that
had already been freed.  This help fix the bug by delaying the
destruction of the BFD reference (and thus the per-bfd object) until
after the registry has been shut down.

1 files changed, 22 insertions, 21 deletions

diff --git a/gdb/elfread.c b/gdb/elfread.c
index e0de52c..08db208 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -211,7 +211,7 @@ record_minimal_symbol (minimal_symbol_reader &reader,
      create an msymbol that references an uninitialised section object.  */
   int section_index = 0;
   if ((bfd_section_flags (bfd_section) & SEC_ALLOC) == SEC_ALLOC)
-    section_index = gdb_bfd_section_index (objfile->obfd, bfd_section);
+    section_index = gdb_bfd_section_index (objfile->obfd.get (), bfd_section);
 
   struct minimal_symbol *result
     = reader.record_full (name, copy_name, address, ms_type, section_index);
@@ -252,7 +252,7 @@ elf_symtab_read (minimal_symbol_reader &reader,
   /* Name of the last file symbol.  This is either a constant string or is
      saved on the objfile's filename cache.  */
   const char *filesymname = "";
-  int stripped = (bfd_get_symcount (objfile->obfd) == 0);
+  int stripped = (bfd_get_symcount (objfile->obfd.get ()) == 0);
   int elf_make_msymbol_special_p
     = gdbarch_elf_make_msymbol_special_p (gdbarch);
 
@@ -271,7 +271,7 @@ elf_symtab_read (minimal_symbol_reader &reader,
       /* Skip "special" symbols, e.g. ARM mapping symbols.  These are
 	 symbols which do not correspond to objects in the symbol table,
 	 but have some other target-specific meaning.  */
-      if (bfd_is_target_special_symbol (objfile->obfd, sym))
+      if (bfd_is_target_special_symbol (objfile->obfd.get (), sym))
 	{
 	  if (gdbarch_record_special_symbol_p (gdbarch))
 	    gdbarch_record_special_symbol (gdbarch, objfile, sym);
@@ -283,7 +283,7 @@ elf_symtab_read (minimal_symbol_reader &reader,
 	  && (sym->flags & BSF_FUNCTION))
 	{
 	  struct minimal_symbol *msym;
-	  bfd *abfd = objfile->obfd;
+	  bfd *abfd = objfile->obfd.get ();
 	  asection *sect;
 
 	  /* Symbol is a reference to a function defined in
@@ -547,7 +547,7 @@ static void
 elf_rel_plt_read (minimal_symbol_reader &reader,
 		  struct objfile *objfile, asymbol **dyn_symbol_table)
 {
-  bfd *obfd = objfile->obfd;
+  bfd *obfd = objfile->obfd.get ();
   const struct elf_backend_data *bed = get_elf_backend_data (obfd);
   asection *relplt, *got_plt;
   bfd_size_type reloc_count, reloc;
@@ -816,7 +816,7 @@ elf_gnu_ifunc_resolve_by_got (const char *name, CORE_ADDR *addr_p)
 
   for (objfile *objfile : current_program_space->objfiles ())
     {
-      bfd *obfd = objfile->obfd;
+      bfd *obfd = objfile->obfd.get ();
       struct gdbarch *gdbarch = objfile->arch ();
       struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
       size_t ptr_size = TYPE_LENGTH (ptr_type);
@@ -1041,7 +1041,7 @@ static void
 elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags,
 			  const struct elfinfo *ei)
 {
-  bfd *synth_abfd, *abfd = objfile->obfd;
+  bfd *synth_abfd, *abfd = objfile->obfd.get ();
   long symcount = 0, dynsymcount = 0, synthcount, storage_needed;
   asymbol **symbol_table = NULL, **dyn_symbol_table = NULL;
   asymbol *synthsyms;
@@ -1067,10 +1067,10 @@ elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags,
 
   /* Process the normal ELF symbol table first.  */
 
-  storage_needed = bfd_get_symtab_upper_bound (objfile->obfd);
+  storage_needed = bfd_get_symtab_upper_bound (objfile->obfd.get ());
   if (storage_needed < 0)
     error (_("Can't read symbols from %s: %s"),
-	   bfd_get_filename (objfile->obfd),
+	   bfd_get_filename (objfile->obfd.get ()),
 	   bfd_errmsg (bfd_get_error ()));
 
   if (storage_needed > 0)
@@ -1079,11 +1079,11 @@ elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags,
 	 bfd_canonicalize_symtab so it must not get freed before ABFD gets.  */
 
       symbol_table = (asymbol **) bfd_alloc (abfd, storage_needed);
-      symcount = bfd_canonicalize_symtab (objfile->obfd, symbol_table);
+      symcount = bfd_canonicalize_symtab (objfile->obfd.get (), symbol_table);
 
       if (symcount < 0)
 	error (_("Can't read symbols from %s: %s"),
-	       bfd_get_filename (objfile->obfd),
+	       bfd_get_filename (objfile->obfd.get ()),
 	       bfd_errmsg (bfd_get_error ()));
 
       elf_symtab_read (reader, objfile, ST_REGULAR, symcount, symbol_table,
@@ -1092,7 +1092,7 @@ elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags,
 
   /* Add the dynamic symbols.  */
 
-  storage_needed = bfd_get_dynamic_symtab_upper_bound (objfile->obfd);
+  storage_needed = bfd_get_dynamic_symtab_upper_bound (objfile->obfd.get ());
 
   if (storage_needed > 0)
     {
@@ -1104,12 +1104,12 @@ elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags,
 	 implementation detail, though.  */
 
       dyn_symbol_table = (asymbol **) bfd_alloc (abfd, storage_needed);
-      dynsymcount = bfd_canonicalize_dynamic_symtab (objfile->obfd,
+      dynsymcount = bfd_canonicalize_dynamic_symtab (objfile->obfd.get (),
 						     dyn_symbol_table);
 
       if (dynsymcount < 0)
 	error (_("Can't read symbols from %s: %s"),
-	       bfd_get_filename (objfile->obfd),
+	       bfd_get_filename (objfile->obfd.get ()),
 	       bfd_errmsg (bfd_get_error ()));
 
       elf_symtab_read (reader, objfile, ST_DYNAMIC, dynsymcount,
@@ -1131,7 +1131,7 @@ elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags,
      backlinked binary where it is valid.  */
 
   if (objfile->separate_debug_objfile_backlink)
-    synth_abfd = objfile->separate_debug_objfile_backlink->obfd;
+    synth_abfd = objfile->separate_debug_objfile_backlink->obfd.get ();
   else
     synth_abfd = abfd;
 
@@ -1193,7 +1193,7 @@ elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags,
 static void
 elf_symfile_read (struct objfile *objfile, symfile_add_flags symfile_flags)
 {
-  bfd *abfd = objfile->obfd;
+  bfd *abfd = objfile->obfd.get ();
   struct elfinfo ei;
   bool has_dwarf2 = true;
 
@@ -1271,13 +1271,14 @@ elf_symfile_read (struct objfile *objfile, symfile_add_flags symfile_flags)
 	{
 	  gdb_bfd_ref_ptr debug_bfd (symfile_bfd_open (debugfile.c_str ()));
 
-	  symbol_file_add_separate (debug_bfd.get (), debugfile.c_str (),
+	  symbol_file_add_separate (debug_bfd, debugfile.c_str (),
 				    symfile_flags, objfile);
 	}
       else
 	{
 	  has_dwarf2 = false;
-	  const struct bfd_build_id *build_id = build_id_bfd_get (objfile->obfd);
+	  const struct bfd_build_id *build_id
+	    = build_id_bfd_get (objfile->obfd.get ());
 
 	  if (build_id != nullptr)
 	    {
@@ -1297,7 +1298,7 @@ elf_symfile_read (struct objfile *objfile, symfile_add_flags symfile_flags)
 			     objfile->original_name);
 		  else if (build_id_verify (debug_bfd.get (), build_id->size, build_id->data))
 		    {
-		      symbol_file_add_separate (debug_bfd.get (), symfile_path.get (),
+		      symbol_file_add_separate (debug_bfd, symfile_path.get (),
 						symfile_flags, objfile);
 		      has_dwarf2 = true;
 		    }
@@ -1348,11 +1349,11 @@ elf_symfile_init (struct objfile *objfile)
 static const elfread_data &
 elf_get_probes (struct objfile *objfile)
 {
-  elfread_data *probes_per_bfd = probe_key.get (objfile->obfd);
+  elfread_data *probes_per_bfd = probe_key.get (objfile->obfd.get ());
 
   if (probes_per_bfd == NULL)
     {
-      probes_per_bfd = probe_key.emplace (objfile->obfd);
+      probes_per_bfd = probe_key.emplace (objfile->obfd.get ());
 
       /* Here we try to gather information about all types of probes from the
 	 objfile.  */