Fix illegal memory accesses trigeered when linking corrupt input files.

	PR 23055
	* aoutx.h (find_nearest_line): Check that the symbol name exists
	and is long enough, before attempting to see if it is for a .o
	file.
	* hash.c (bfd_hash_hash): Add an assertion that the string is not
	NULL.
	* linker.c (bfd_link_hash_lookup): Fail if the table or string are
	NULL.
	(_bfd_generic_link_add_archive_symbols): Fail if an archive entry
	has no name.

4 files changed, 24 insertions, 3 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index eb283d6..88365d0 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,5 +1,16 @@
 2018-04-17  Nick Clifton  <nickc@redhat.com>
 
+	PR 23055
+	* aoutx.h (find_nearest_line): Check that the symbol name exists
+	and is long enough, before attempting to see if it is for a .o
+	file.
+	* hash.c (bfd_hash_hash): Add an assertion that the string is not
+	NULL.
+	* linker.c (bfd_link_hash_lookup): Fail if the table or string are
+	NULL.
+	(_bfd_generic_link_add_archive_symbols): Fail if an archive entry
+	has no name.
+
 	PR 23065
 	* dwarf2.c (concat_filename): Check for a NULL table pointer.
 
diff --git a/bfd/aoutx.h b/bfd/aoutx.h
index 0e0bab0..7cc9561 100644
--- a/bfd/aoutx.h
+++ b/bfd/aoutx.h
@@ -2723,7 +2723,10 @@ NAME (aout, find_nearest_line) (bfd *abfd,
 		  const char *symname;
 
 		  symname = q->symbol.name;
-		  if (strcmp (symname + strlen (symname) - 2, ".o") == 0)
+
+		  if (symname != NULL
+		      && strlen (symname) > 2
+		      && strcmp (symname + strlen (symname) - 2, ".o") == 0)
 		    {
 		      if (q->symbol.value > low_line_vma)
 			{
@@ -2788,8 +2791,8 @@ NAME (aout, find_nearest_line) (bfd *abfd,
 	    case N_FUN:
 	      {
 		/* We'll keep this if it is nearer than the one we have already.  */
-		if (q->symbol.value >= low_func_vma &&
-		    q->symbol.value <= offset)
+		if (q->symbol.value >= low_func_vma
+		    && q->symbol.value <= offset)
 		  {
 		    low_func_vma = q->symbol.value;
 		    func = (asymbol *)q;
diff --git a/bfd/hash.c b/bfd/hash.c
index 43c6005..852a95e 100644
--- a/bfd/hash.c
+++ b/bfd/hash.c
@@ -435,6 +435,7 @@ bfd_hash_hash (const char *string, unsigned int *lenp)
   unsigned int len;
   unsigned int c;
 
+  BFD_ASSERT (string != NULL);
   hash = 0;
   len = 0;
   s = (const unsigned char *) string;
diff --git a/bfd/linker.c b/bfd/linker.c
index c29a6e7..3019919 100644
--- a/bfd/linker.c
+++ b/bfd/linker.c
@@ -495,6 +495,9 @@ bfd_link_hash_lookup (struct bfd_link_hash_table *table,
 {
   struct bfd_link_hash_entry *ret;
 
+  if (table == NULL || string == NULL)
+    return NULL;
+
   ret = ((struct bfd_link_hash_entry *)
 	 bfd_hash_lookup (&table->table, string, create, copy));
 
@@ -941,6 +944,9 @@ _bfd_generic_link_add_archive_symbols
 	      continue;
 	    }
 
+	  if (arsym->name == NULL)
+	    goto error_return;
+				  
 	  h = bfd_link_hash_lookup (info->hash, arsym->name,
 				    FALSE, FALSE, TRUE);