XCOFF ld segfaults when running ld testsuite

The binutils XCOFF support doesn't handle random linker scripts very
well at all.  These tweaks to final_link fix segfaults when some
linker created sections are discarded due to "/DISCARD/ : { *(.*) }"
in scripts.  The xcoff_mark change is necessary to not segfault on
symbols defined in scripts, which may be bfd_link_hash_defined yet
have u.def.section set to bfd_und_section_ptr.  (Which might seem odd,
but occurs during early stages of linking before input sections are
mapped.)

	* xcofflink.c (xcoff_mark): Don't mark const sections.
	(bfd_xcoff_record_link_assignment): Add FIXME.
	(_bfd_xcoff_bfd_final_link): Don't segfault on assorted magic
	sections being discarded by linker script.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 580edfe41ea943ddc16998dad21a4cc34077226b..7511be9fdcb98ddddfe1839efe6a3be87a5fbc66 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,10 @@
+2020-07-07  Alan Modra  <amodra@gmail.com>
+
+       * xcofflink.c (xcoff_mark): Don't mark const sections.
+       (bfd_xcoff_record_link_assignment): Add FIXME.
+       (_bfd_xcoff_bfd_final_link): Don't segfault on assorted magic
+       sections being discarded by linker script.
+
 2020-07-07  Alan Modra  <amodra@gmail.com>
 
        * coff-rs6000.c (xcoff_write_archive_contents_old): Set default

diff --git a/bfd/xcofflink.c b/bfd/xcofflink.c
index 4497be25291b7c278c76f520f7df9f3fe40cf11b..985e2217429242d6ab57a041fb84569db014a632 100644 (file)
--- a/bfd/xcofflink.c
+++ b/bfd/xcofflink.c
@@ -2898,7 +2898,7 @@ xcoff_mark_symbol_by_name (struct bfd_link_info *info,
 static bfd_boolean
 xcoff_mark (struct bfd_link_info *info, asection *sec)
 {
-  if (bfd_is_abs_section (sec)
+  if (bfd_is_const_section (sec)
       || (sec->flags & SEC_MARK) != 0)
     return TRUE;
 
@@ -3210,7 +3210,13 @@ bfd_xcoff_link_count_reloc (bfd *output_bfd,
 }
 
 /* This function is called for each symbol to which the linker script
-   assigns a value.  */
+   assigns a value.
+   FIXME: In cases like the linker test ld-scripts/defined5 where a
+   symbol is defined both by an input object file and the script,
+   the script definition doesn't override the object file definition
+   as is usual for other targets.  At least not when the symbol is
+   output.  Other uses of the symbol value by the linker do use the
+   script value.  */
 
 bfd_boolean
 bfd_xcoff_record_link_assignment (bfd *output_bfd,
@@ -6327,7 +6333,9 @@ _bfd_xcoff_bfd_final_link (bfd *abfd, struct bfd_link_info *info)
 
   /* Write out the loader section contents.  */
   o = xcoff_hash_table (info)->loader_section;
-  if (o)
+  if (o != NULL
+      && o->size != 0
+      && o->output_section != bfd_abs_section_ptr)
     {
       BFD_ASSERT ((bfd_byte *) flinfo.ldrel
                  == (xcoff_hash_table (info)->loader_section->contents
@@ -6339,19 +6347,25 @@ _bfd_xcoff_bfd_final_link (bfd *abfd, struct bfd_link_info *info)
 
   /* Write out the magic sections.  */
   o = xcoff_hash_table (info)->linkage_section;
-  if (o->size > 0
+  if (o != NULL
+      && o->size != 0
+      && o->output_section != bfd_abs_section_ptr
       && ! bfd_set_section_contents (abfd, o->output_section, o->contents,
                                     (file_ptr) o->output_offset,
                                     o->size))
     goto error_return;
   o = xcoff_hash_table (info)->toc_section;
-  if (o->size > 0
+  if (o != NULL
+      && o->size != 0
+      && o->output_section != bfd_abs_section_ptr
       && ! bfd_set_section_contents (abfd, o->output_section, o->contents,
                                     (file_ptr) o->output_offset,
                                     o->size))
     goto error_return;
   o = xcoff_hash_table (info)->descriptor_section;
-  if (o->size > 0
+  if (o != NULL
+      && o->size != 0
+      && o->output_section != bfd_abs_section_ptr
       && ! bfd_set_section_contents (abfd, o->output_section, o->contents,
                                     (file_ptr) o->output_offset,
                                     o->size))
@@ -6374,7 +6388,9 @@ _bfd_xcoff_bfd_final_link (bfd *abfd, struct bfd_link_info *info)
 
   /* Write out the debugging string table.  */
   o = xcoff_hash_table (info)->debug_section;
-  if (o != NULL)
+  if (o != NULL
+      && o->size != 0
+      && o->output_section != bfd_abs_section_ptr)
     {
       struct bfd_strtab_hash *debug_strtab;