From 3f85007dfb37badab0def30cf7bb40b0bdb2ccd8 Mon Sep 17 00:00:00 2001
From: Chaskiel M Grundman <cg2v@andrew.cmu.edu>
Date: Tue, 20 Mar 2007 18:48:52 +0000
Subject: [PATCH] STABLE14-linux-task-pointer-safety-20070320

hold applicable locks while futzing with task list


(cherry picked from commit 29951ff73ccc82746f8f842131a76e30b47d5310)
---
 src/afs/LINUX/osi_groups.c | 25 ++++++++++++++++++-
 src/rx/LINUX/rx_knet.c     | 50 ++++++++++++++++++++------------------
 2 files changed, 51 insertions(+), 24 deletions(-)

diff --git a/src/afs/LINUX/osi_groups.c b/src/afs/LINUX/osi_groups.c
index 997ec7a684..c0d8270279 100644
--- a/src/afs/LINUX/osi_groups.c
+++ b/src/afs/LINUX/osi_groups.c
@@ -617,13 +617,36 @@ struct key_type key_type_afs_pag =
     .destroy     = afs_pag_destroy,
 };
 
+#ifdef EXPORTED_TASKLIST_LOCK
+extern rwlock_t tasklist_lock __attribute__((weak));
+#endif
+
 void osi_keyring_init(void)
 {
     struct task_struct *p;
-
+#ifdef EXPORTED_TASKLIST_LOCK
+    if (&tasklist_lock)
+      read_lock(&tasklist_lock);
+#endif
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+#ifdef EXPORTED_TASKLIST_LOCK
+    else
+#endif
+      rcu_read_lock();
+#endif
     p = find_task_by_pid(1);
     if (p && p->user->session_keyring)
 	__key_type_keyring = p->user->session_keyring->type;
+#ifdef EXPORTED_TASKLIST_LOCK
+    if (&tasklist_lock)
+       read_unlock(&tasklist_lock);
+#endif
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+#ifdef EXPORTED_TASKLIST_LOCK
+    else
+#endif
+      rcu_read_unlock();
+#endif
 
     register_key_type(&key_type_afs_pag);
 }
diff --git a/src/rx/LINUX/rx_knet.c b/src/rx/LINUX/rx_knet.c
index 8587b0d0ac..f1b366769a 100644
--- a/src/rx/LINUX/rx_knet.c
+++ b/src/rx/LINUX/rx_knet.c
@@ -213,30 +213,34 @@ osi_StopListener(void)
     struct task_struct *listener;
     extern int rxk_ListenerPid;
 
-#ifdef EXPORTED_TASKLIST_LOCK
-    if (&tasklist_lock)
-      read_lock(&tasklist_lock);
-#endif
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
-#ifdef EXPORTED_TASKLIST_LOCK
-    else
-#endif
-      rcu_read_lock();
-#endif
-    listener = find_task_by_pid(rxk_ListenerPid);
-#ifdef EXPORTED_TASKLIST_LOCK
-    if (&tasklist_lock)
-       read_unlock(&tasklist_lock);
-#endif
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
-#ifdef EXPORTED_TASKLIST_LOCK
-    else
-#endif
-      rcu_read_unlock();
-#endif
     while (rxk_ListenerPid) {
-	flush_signals(listener);
-	force_sig(SIGKILL, listener);
+#ifdef EXPORTED_TASKLIST_LOCK
+	if (&tasklist_lock)
+	   read_lock(&tasklist_lock);
+#endif
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+#ifdef EXPORTED_TASKLIST_LOCK
+	else
+#endif
+	   rcu_read_lock();
+#endif
+	listener = find_task_by_pid(rxk_ListenerPid);
+        if (listener) {
+	    flush_signals(listener);
+	    force_sig(SIGKILL, listener);
+	}
+#ifdef EXPORTED_TASKLIST_LOCK
+	if (&tasklist_lock)
+	    read_unlock(&tasklist_lock);
+#endif
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+#ifdef EXPORTED_TASKLIST_LOCK
+	else
+#endif
+	   rcu_read_unlock();
+#endif
+	if (!listener)
+	    break;
 	afs_osi_Sleep(&rxk_ListenerPid);
     }
     sock_release(rx_socket);