PR25022 testcase segfault for generic ELF linker targets

Even a testcase that is expected to fail shouldn't segfault.

	* elf.c (assign_section_numbers): Comment.  Don't segfault on
	discarded sections when setting linked-to section for generic
	ELF linker.
	* elflink.c (bfd_elf_match_symbols_in_sections): Allow NULL info.

3 files changed, 36 insertions, 39 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index dfc3cbc..1e7fb4a 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,10 @@
+2020-07-28  Alan Modra  <amodra@gmail.com>
+
+	* elf.c (assign_section_numbers): Comment.  Don't segfault on
+	discarded sections when setting linked-to section for generic
+	ELF linker.
+	* elflink.c (bfd_elf_match_symbols_in_sections): Allow NULL info.
+
 2020-07-27  Alan Modra  <amodra@gmail.com>
 
 	* xcofflink.c (xcoff_need_ldrel_p): Accept --just-symbols symbols and
diff --git a/bfd/elf.c b/bfd/elf.c
index 991a71c..59fde16 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -3704,7 +3704,8 @@ elf_get_reloc_section (asection *reloc_sec)
 
 /* Assign all ELF section numbers.  The dummy first section is handled here
    too.  The link/info pointers for the standard section types are filled
-   in here too, while we're at it.  */
+   in here too, while we're at it.  LINK_INFO will be 0 when arriving
+   here for objcopy, and when using the generic ELF linker.  */
 
 static bfd_boolean
 assign_section_numbers (bfd *abfd, struct bfd_link_info *link_info)
@@ -3889,48 +3890,37 @@ assign_section_numbers (bfd *abfd, struct bfd_link_info *link_info)
 	  s = elf_linked_to_section (sec);
 	  if (s)
 	    {
-	      /* elf_linked_to_section points to the input section.  */
-	      if (link_info != NULL)
+	      /* Check discarded linkonce section.  */
+	      if (discarded_section (s))
 		{
-		  /* Check discarded linkonce section.  */
-		  if (discarded_section (s))
-		    {
-		      asection *kept;
-		      _bfd_error_handler
-			/* xgettext:c-format */
-			(_("%pB: sh_link of section `%pA' points to"
-			   " discarded section `%pA' of `%pB'"),
-			 abfd, d->this_hdr.bfd_section,
-			 s, s->owner);
-		      /* Point to the kept section if it has the same
-			 size as the discarded one.  */
-		      kept = _bfd_elf_check_kept_section (s, link_info);
-		      if (kept == NULL)
-			{
-			  bfd_set_error (bfd_error_bad_value);
-			  return FALSE;
-			}
-		      s = kept;
-		    }
-
-		  s = s->output_section;
-		  BFD_ASSERT (s != NULL);
-		}
-	      else
-		{
-		  /* Handle objcopy. */
-		  if (s->output_section == NULL)
+		  asection *kept;
+		  _bfd_error_handler
+		    /* xgettext:c-format */
+		    (_("%pB: sh_link of section `%pA' points to"
+		       " discarded section `%pA' of `%pB'"),
+		     abfd, d->this_hdr.bfd_section, s, s->owner);
+		  /* Point to the kept section if it has the same
+		     size as the discarded one.  */
+		  kept = _bfd_elf_check_kept_section (s, link_info);
+		  if (kept == NULL)
 		    {
-		      _bfd_error_handler
-			/* xgettext:c-format */
-			(_("%pB: sh_link of section `%pA' points to"
-			   " removed section `%pA' of `%pB'"),
-			 abfd, d->this_hdr.bfd_section, s, s->owner);
 		      bfd_set_error (bfd_error_bad_value);
 		      return FALSE;
 		    }
-		  s = s->output_section;
+		  s = kept;
+		}
+	      /* Handle objcopy. */
+	      else if (s->output_section == NULL)
+		{
+		  _bfd_error_handler
+		    /* xgettext:c-format */
+		    (_("%pB: sh_link of section `%pA' points to"
+		       " removed section `%pA' of `%pB'"),
+		     abfd, d->this_hdr.bfd_section, s, s->owner);
+		  bfd_set_error (bfd_error_bad_value);
+		  return FALSE;
 		}
+	      s = s->output_section;
 	      d->this_hdr.sh_link = elf_section_data (s)->this_idx;
 	    }
 	  else
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 286fc11..a3823e6 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -8179,7 +8179,7 @@ bfd_elf_match_symbols_in_sections (asection *sec1, asection *sec2,
       if (isymbuf1 == NULL)
 	goto done;
 
-      if (!info->reduce_memory_overheads)
+      if (info != NULL && !info->reduce_memory_overheads)
 	{
 	  ssymbuf1 = elf_create_symbuf (symcount1, isymbuf1);
 	  elf_tdata (bfd1)->symbuf = ssymbuf1;
@@ -8193,7 +8193,7 @@ bfd_elf_match_symbols_in_sections (asection *sec1, asection *sec2,
       if (isymbuf2 == NULL)
 	goto done;
 
-      if (ssymbuf1 != NULL && !info->reduce_memory_overheads)
+      if (ssymbuf1 != NULL && info != NULL && !info->reduce_memory_overheads)
 	{
 	  ssymbuf2 = elf_create_symbuf (symcount2, isymbuf2);
 	  elf_tdata (bfd2)->symbuf = ssymbuf2;