Fix potential crashes when Target::make_symbol() returns NULL.

2016-08-10  James Clarke  <jrtc27@jrtc27.com>

gold/
	PR gold/20443
	* symtab.cc (Symbol_table::add_from_relobj): Handle NULL symbols,
	which will be present for STT_SPARC_REGISTER.
	(Symbol_table::add_from_pluginobj): Likewise.
	(Symbol_table::add_from_dynobj): Likewise.
	(Symbol_table::add_from_incrobj): Removed dead code.

1 files changed, 9 insertions, 4 deletions

diff --git a/gold/symtab.cc b/gold/symtab.cc
index 5ce5c31bfee..b31794a5a8c 100644
--- a/gold/symtab.cc
+++ b/gold/symtab.cc
@@ -1325,6 +1325,9 @@ Symbol_table::add_from_relobj(
       res = this->add_from_object(relobj, name, name_key, ver, ver_key,
 				  is_default_version, *psym, st_shndx,
 				  is_ordinary, orig_st_shndx);
+
+      if (res == NULL)
+	continue;
       
       if (is_forced_local)
 	this->force_local(res);
@@ -1406,6 +1409,9 @@ Symbol_table::add_from_pluginobj(
 		              is_default_version, *sym, st_shndx,
 			      is_ordinary, st_shndx);
 
+  if (res == NULL)
+    return NULL;
+
   if (is_forced_local)
     this->force_local(res);
 
@@ -1602,6 +1608,9 @@ Symbol_table::add_from_dynobj(
 	    }
 	}
 
+      if (res == NULL)
+	continue;
+
       // Note that it is possible that RES was overridden by an
       // earlier object, in which case it can't be aliased here.
       if (st_shndx != elfcpp::SHN_UNDEF
@@ -1640,7 +1649,6 @@ Symbol_table::add_from_incrobj(
 
   Stringpool::Key ver_key = 0;
   bool is_default_version = false;
-  bool is_forced_local = false;
 
   Stringpool::Key name_key;
   name = this->namepool_.add(name, true, &name_key);
@@ -1650,9 +1658,6 @@ Symbol_table::add_from_incrobj(
 		              is_default_version, *sym, st_shndx,
 			      is_ordinary, st_shndx);
 
-  if (is_forced_local)
-    this->force_local(res);
-
   return res;
 }