From 5d8eb435a8f2f2af2babe76a0e88a54b2668c3c7 Mon Sep 17 00:00:00 2001
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Sun, 2 Jan 2022 04:09:30 +0100
Subject: [PATCH] hurd: nuke all unknown ports on exec

Ports which are not in the ports table or dtable will not make sense for the
new program, so we can nuke them.  Actually we shall, otherwise we would
be leaking various ports, for instance the file_t of the executed program
itself.
---
 hurd/hurdexec.c | 46 +++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 39 insertions(+), 7 deletions(-)

diff --git a/hurd/hurdexec.c b/hurd/hurdexec.c
index 5b27f1861b..546cc69960 100644
--- a/hurd/hurdexec.c
+++ b/hurd/hurdexec.c
@@ -65,12 +65,16 @@ _hurd_exec_paths (task_t task, file_t file,
       _hurd_port_free (&_hurd_ports[i], &ulink_ports[i], ports[i]);
     }
   file_t *dtable;
-  unsigned int dtablesize, i;
+  unsigned int dtablesize, i, j;
   struct hurd_port **dtable_cells;
   struct hurd_userlink *ulink_dtable;
   struct hurd_sigstate *ss;
   mach_port_t *please_dealloc, *pdp;
   int reauth = 0;
+  mach_port_t *portnames = NULL;
+  mach_msg_type_number_t nportnames = 0;
+  mach_port_type_t *porttypes = NULL;
+  mach_msg_type_number_t nporttypes = 0;
 
   /* XXX needs to be hurdmalloc XXX */
   if (argv == NULL)
@@ -361,6 +365,15 @@ retry:
 
       if (pdp)
 	{
+	  /* Get all ports that we may not know about and we should thus destroy.  */
+	  /* XXX need to disable other threads to be safe.  */
+	  if (err = __mach_port_names (__mach_task_self (),
+				     &portnames, &nportnames,
+				     &porttypes, &nporttypes))
+	    return err;
+	  if (nportnames != nporttypes)
+	    return EGRATUITOUS;
+
 	  /* Request the exec server to deallocate some ports from us if
 	     the exec succeeds.  The init ports and descriptor ports will
 	     arrive in the new program's exec_startup message.  If we
@@ -370,9 +383,30 @@ retry:
 	     exec call.  */
 
 	  for (i = 0; i < _hurd_nports; ++i)
-	    *pdp++ = ports[i];
+	    {
+	      *pdp++ = ports[i];
+	      for (j = 0; j < nportnames; j++)
+		if (portnames[j] == ports[i])
+		  portnames[j] = MACH_PORT_NULL;
+	    }
 	  for (i = 0; i < dtablesize; ++i)
-	    *pdp++ = dtable[i];
+	    {
+	      *pdp++ = dtable[i];
+	      for (j = 0; j < nportnames; j++)
+		if (portnames[j] == dtable[i])
+		  portnames[j] = MACH_PORT_NULL;
+	    }
+
+	  /* Pack ports to be destroyed together.  */
+	  for (i = 0, j = 0; i < nportnames; i++)
+	    {
+	      if (portnames[i] == MACH_PORT_NULL)
+		continue;
+	      if (j != i)
+		portnames[j] = portnames[i];
+	      j++;
+	    }
+	  nportnames = j;
 	}
 
       flags = 0;
@@ -393,8 +427,7 @@ retry:
 			       _hurd_nports,
 			       ints, INIT_INT_MAX,
 			       please_dealloc, pdp - please_dealloc,
-			       &_hurd_msgport,
-			       task == __mach_task_self () ? 1 : 0);
+			       portnames, nportnames);
       /* Fall back for backwards compatibility.  This can just be removed
          when __file_exec goes away.  */
       if (err == MIG_BAD_ID)
@@ -404,8 +437,7 @@ retry:
 			   ports, MACH_MSG_TYPE_COPY_SEND, _hurd_nports,
 			   ints, INIT_INT_MAX,
 			   please_dealloc, pdp - please_dealloc,
-			   &_hurd_msgport,
-			   task == __mach_task_self () ? 1 : 0);
+			   portnames, nportnames);
     }
 
   /* Release references to the standard ports.  */