OTP-8487 unregister/1 on a port can cause the non-smp runtime to crash

A call to the BIF unregister(RegName) when a port had the name RegName
registered in the runtime system without SMP support caused a runtime
system crash. (Thanks to Per Hedeland for the bugfix and test case.)

2 files changed, 24 insertions, 15 deletions

diff --git a/erts/emulator/beam/register.c b/erts/emulator/beam/register.c
index 7ba097382a..964c10a380 100644
--- a/erts/emulator/beam/register.c
+++ b/erts/emulator/beam/register.c
@@ -1,19 +1,19 @@
 /*
  * %CopyrightBegin%
- * 
- * Copyright Ericsson AB 1996-2009. All Rights Reserved.
- * 
+ *
+ * Copyright Ericsson AB 1996-2010. All Rights Reserved.
+ *
  * The contents of this file are subject to the Erlang Public License,
  * Version 1.1, (the "License"); you may not use this file except in
  * compliance with the License. You should have received a copy of the
  * Erlang Public License along with this software. If not, it can be
  * retrieved online at http://www.erlang.org/.
- * 
+ *
  * Software distributed under the License is distributed on an "AS IS"
  * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
  * the License for the specific language governing rights and limitations
  * under the License.
- * 
+ *
  * %CopyrightEnd%
  */
 
@@ -500,8 +500,8 @@ int erts_unregister_name(Process *c_p,
 
     if ((rp = (RegProc*) hash_get(&process_reg, (void*) &r)) != NULL) {
 	if (rp->pt) {
-#ifdef ERTS_SMP
 	    if (port != rp->pt) {
+#ifdef ERTS_SMP
 		if (port) {
 		    ERTS_SMP_LC_ASSERT(port != c_prt);
 		    erts_smp_port_unlock(port);
@@ -519,10 +519,13 @@ int erts_unregister_name(Process *c_p,
 		    port = erts_id2port(id, NULL, 0);
 		    goto restart;
 		}
+#endif
 		port = rp->pt;
 	    }
-#endif
-	    ERTS_SMP_LC_ASSERT(rp->pt == port && erts_lc_is_port_locked(port));
+
+	    ASSERT(rp->pt == port);
+	    ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(port));
+
 	    rp->pt->reg = NULL;
 	    
 	    if (IS_TRACED_FL(port, F_TRACE_PORTS)) {
diff --git a/erts/emulator/test/port_SUITE.erl b/erts/emulator/test/port_SUITE.erl
index 9a09d20eab..b9100738e4 100644
--- a/erts/emulator/test/port_SUITE.erl
+++ b/erts/emulator/test/port_SUITE.erl
@@ -1,19 +1,19 @@
 %%
 %% %CopyrightBegin%
-%% 
-%% Copyright Ericsson AB 1997-2009. All Rights Reserved.
-%% 
+%%
+%% Copyright Ericsson AB 1997-2010. All Rights Reserved.
+%%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
 %% compliance with the License. You should have received a copy of the
 %% Erlang Public License along with this software. If not, it can be
 %% retrieved online at http://www.erlang.org/.
-%% 
+%%
 %% Software distributed under the License is distributed on an "AS IS"
 %% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 %% the License for the specific language governing rights and limitations
 %% under the License.
-%% 
+%%
 %% %CopyrightEnd%
 %%
 
@@ -88,7 +88,8 @@
 	 otp_3906/1, otp_4389/1, win_massive/1, win_massive_client/1,
 	 mix_up_ports/1, otp_5112/1, otp_5119/1, otp_6224/1,
 	 exit_status_multi_scheduling_block/1, ports/1,
-	 spawn_driver/1,spawn_executable/1]).
+	 spawn_driver/1,spawn_executable/1,
+	 unregister_name/1]).
 
 -export([]).
 
@@ -112,7 +113,8 @@ all(suite) ->
      otp_3906, otp_4389, win_massive, mix_up_ports,
      otp_5112, otp_5119,
      exit_status_multi_scheduling_block,
-     ports, spawn_driver, spawn_executable
+     ports, spawn_driver, spawn_executable,
+     unregister_name
     ].
 
 -define(DEFAULT_TIMEOUT, ?t:minutes(5)).
@@ -1434,6 +1436,10 @@ spawn_executable(Config) when is_list(Config) ->
     ?line test_server:timetrap_cancel(Dog),
     ok.
 
+unregister_name(Config) when is_list(Config) ->
+    ?line true = register(crash, open_port({spawn, "sleep 100"}, [])),
+    ?line true = unregister(crash).
+
 test_bat_file(Dir) ->
     FN = "tf.bat",
     Full = filename:join([Dir,FN]),