Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull security subsystem updates from James Morris:
 "A quiet cycle for the security subsystem with just a few maintenance
  updates."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  Smack: create a sysfs mount point for smackfs
  Smack: use select not depends in Kconfig
  Yama: remove locking from delete path
  Yama: add RCU to drop read locking
  drivers/char/tpm: remove tasklet and cleanup
  KEYS: Use keyring_alloc() to create special keyrings
  KEYS: Reduce initial permissions on keys
  KEYS: Make the session and process keyrings per-thread
  seccomp: Make syscall skipping and nr changes more consistent
  key: Fix resource leak
  keys: Fix unreachable code
  KEYS: Add payload preparsing opportunity prior to key instantiate or update

8 files changed, 153 insertions, 102 deletions

diff --git a/security/keys/key.c b/security/keys/key.c
index a15c9da..8fb7c7b 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -854,13 +854,13 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
 	/* if the client doesn't provide, decide on the permissions we want */
 	if (perm == KEY_PERM_UNDEF) {
 		perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
-		perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR;
+		perm |= KEY_USR_VIEW;
 
 		if (ktype->read)
-			perm |= KEY_POS_READ | KEY_USR_READ;
+			perm |= KEY_POS_READ;
 
 		if (ktype == &key_type_keyring || ktype->update)
-			perm |= KEY_USR_WRITE;
+			perm |= KEY_POS_WRITE;
 	}
 
 	/* allocate a new key */
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 5d34b4e..4b5c948 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1132,12 +1132,12 @@ long keyctl_instantiate_key_iov(key_serial_t id,
 	ret = rw_copy_check_uvector(WRITE, _payload_iov, ioc,
 				    ARRAY_SIZE(iovstack), iovstack, &iov);
 	if (ret < 0)
-		return ret;
+		goto err;
 	if (ret == 0)
 		goto no_payload_free;
 
 	ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
-
+err:
 	if (iov != iovstack)
 		kfree(iov);
 	return ret;
@@ -1495,7 +1495,8 @@ long keyctl_session_to_parent(void)
 		goto error_keyring;
 	newwork = &cred->rcu;
 
-	cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
+	cred->session_keyring = key_ref_to_ptr(keyring_r);
+	keyring_r = NULL;
 	init_task_work(newwork, key_change_session_keyring);
 
 	me = current;
@@ -1519,7 +1520,7 @@ long keyctl_session_to_parent(void)
 	mycred = current_cred();
 	pcred = __task_cred(parent);
 	if (mycred == pcred ||
-	    mycred->tgcred->session_keyring == pcred->tgcred->session_keyring) {
+	    mycred->session_keyring == pcred->session_keyring) {
 		ret = 0;
 		goto unlock;
 	}
@@ -1535,9 +1536,9 @@ long keyctl_session_to_parent(void)
 		goto unlock;
 
 	/* the keyrings must have the same UID */
-	if ((pcred->tgcred->session_keyring &&
-	     !uid_eq(pcred->tgcred->session_keyring->uid, mycred->euid)) ||
-	    !uid_eq(mycred->tgcred->session_keyring->uid, mycred->euid))
+	if ((pcred->session_keyring &&
+	     !uid_eq(pcred->session_keyring->uid, mycred->euid)) ||
+	    !uid_eq(mycred->session_keyring->uid, mycred->euid))
 		goto unlock;
 
 	/* cancel an already pending keyring replacement */
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 6e42df1..6ece7f2 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -257,17 +257,14 @@ error:
  * Allocate a keyring and link into the destination keyring.
  */
 struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
-			  const struct cred *cred, unsigned long flags,
-			  struct key *dest)
+			  const struct cred *cred, key_perm_t perm,
+			  unsigned long flags, struct key *dest)
 {
 	struct key *keyring;
 	int ret;
 
 	keyring = key_alloc(&key_type_keyring, description,
-			    uid, gid, cred,
-			    (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
-			    flags);
-
+			    uid, gid, cred, perm, flags);
 	if (!IS_ERR(keyring)) {
 		ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
 		if (ret < 0) {
@@ -278,6 +275,7 @@ struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 
 	return keyring;
 }
+EXPORT_SYMBOL(keyring_alloc);
 
 /**
  * keyring_search_aux - Search a keyring tree for a key matching some criteria
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 86468f3..58dfe08 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -45,10 +45,12 @@ int install_user_keyrings(void)
 	struct user_struct *user;
 	const struct cred *cred;
 	struct key *uid_keyring, *session_keyring;
+	key_perm_t user_keyring_perm;
 	char buf[20];
 	int ret;
 	uid_t uid;
 
+	user_keyring_perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL;
 	cred = current_cred();
 	user = cred->user;
 	uid = from_kuid(cred->user_ns, user->uid);
@@ -73,8 +75,8 @@ int install_user_keyrings(void)
 		uid_keyring = find_keyring_by_name(buf, true);
 		if (IS_ERR(uid_keyring)) {
 			uid_keyring = keyring_alloc(buf, user->uid, INVALID_GID,
-						    cred, KEY_ALLOC_IN_QUOTA,
-						    NULL);
+						    cred, user_keyring_perm,
+						    KEY_ALLOC_IN_QUOTA, NULL);
 			if (IS_ERR(uid_keyring)) {
 				ret = PTR_ERR(uid_keyring);
 				goto error;
@@ -89,7 +91,8 @@ int install_user_keyrings(void)
 		if (IS_ERR(session_keyring)) {
 			session_keyring =
 				keyring_alloc(buf, user->uid, INVALID_GID,
-					      cred, KEY_ALLOC_IN_QUOTA, NULL);
+					      cred, user_keyring_perm,
+					      KEY_ALLOC_IN_QUOTA, NULL);
 			if (IS_ERR(session_keyring)) {
 				ret = PTR_ERR(session_keyring);
 				goto error_release;
@@ -130,6 +133,7 @@ int install_thread_keyring_to_cred(struct cred *new)
 	struct key *keyring;
 
 	keyring = keyring_alloc("_tid", new->uid, new->gid, new,
+				KEY_POS_ALL | KEY_USR_VIEW,
 				KEY_ALLOC_QUOTA_OVERRUN, NULL);
 	if (IS_ERR(keyring))
 		return PTR_ERR(keyring);
@@ -170,27 +174,18 @@ static int install_thread_keyring(void)
 int install_process_keyring_to_cred(struct cred *new)
 {
 	struct key *keyring;
-	int ret;
 
-	if (new->tgcred->process_keyring)
+	if (new->process_keyring)
 		return -EEXIST;
 
-	keyring = keyring_alloc("_pid", new->uid, new->gid,
-				new, KEY_ALLOC_QUOTA_OVERRUN, NULL);
+	keyring = keyring_alloc("_pid", new->uid, new->gid, new,
+				KEY_POS_ALL | KEY_USR_VIEW,
+				KEY_ALLOC_QUOTA_OVERRUN, NULL);
 	if (IS_ERR(keyring))
 		return PTR_ERR(keyring);
 
-	spin_lock_irq(&new->tgcred->lock);
-	if (!new->tgcred->process_keyring) {
-		new->tgcred->process_keyring = keyring;
-		keyring = NULL;
-		ret = 0;
-	} else {
-		ret = -EEXIST;
-	}
-	spin_unlock_irq(&new->tgcred->lock);
-	key_put(keyring);
-	return ret;
+	new->process_keyring = keyring;
+	return 0;
 }
 
 /*
@@ -231,11 +226,12 @@ int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
 	/* create an empty session keyring */
 	if (!keyring) {
 		flags = KEY_ALLOC_QUOTA_OVERRUN;
-		if (cred->tgcred->session_keyring)
+		if (cred->session_keyring)
 			flags = KEY_ALLOC_IN_QUOTA;
 
-		keyring = keyring_alloc("_ses", cred->uid, cred->gid,
-					cred, flags, NULL);
+		keyring = keyring_alloc("_ses", cred->uid, cred->gid, cred,
+					KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
+					flags, NULL);
 		if (IS_ERR(keyring))
 			return PTR_ERR(keyring);
 	} else {
@@ -243,17 +239,11 @@ int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
 	}
 
 	/* install the keyring */
-	spin_lock_irq(&cred->tgcred->lock);
-	old = cred->tgcred->session_keyring;
-	rcu_assign_pointer(cred->tgcred->session_keyring, keyring);
-	spin_unlock_irq(&cred->tgcred->lock);
-
-	/* we're using RCU on the pointer, but there's no point synchronising
-	 * on it if it didn't previously point to anything */
-	if (old) {
-		synchronize_rcu();
+	old = cred->session_keyring;
+	rcu_assign_pointer(cred->session_keyring, keyring);
+
+	if (old)
 		key_put(old);
-	}
 
 	return 0;
 }
@@ -368,9 +358,9 @@ key_ref_t search_my_process_keyrings(struct key_type *type,
 	}
 
 	/* search the process keyring second */
-	if (cred->tgcred->process_keyring) {
+	if (cred->process_keyring) {
 		key_ref = keyring_search_aux(
-			make_key_ref(cred->tgcred->process_keyring, 1),
+			make_key_ref(cred->process_keyring, 1),
 			cred, type, description, match, no_state_check);
 		if (!IS_ERR(key_ref))
 			goto found;
@@ -389,12 +379,10 @@ key_ref_t search_my_process_keyrings(struct key_type *type,
 	}
 
 	/* search the session keyring */
-	if (cred->tgcred->session_keyring) {
+	if (cred->session_keyring) {
 		rcu_read_lock();
 		key_ref = keyring_search_aux(
-			make_key_ref(rcu_dereference(
-					     cred->tgcred->session_keyring),
-				     1),
+			make_key_ref(rcu_dereference(cred->session_keyring), 1),
 			cred, type, description, match, no_state_check);
 		rcu_read_unlock();
 
@@ -564,7 +552,7 @@ try_again:
 		break;
 
 	case KEY_SPEC_PROCESS_KEYRING:
-		if (!cred->tgcred->process_keyring) {
+		if (!cred->process_keyring) {
 			if (!(lflags & KEY_LOOKUP_CREATE))
 				goto error;
 
@@ -576,13 +564,13 @@ try_again:
 			goto reget_creds;
 		}
 
-		key = cred->tgcred->process_keyring;
+		key = cred->process_keyring;
 		atomic_inc(&key->usage);
 		key_ref = make_key_ref(key, 1);
 		break;
 
 	case KEY_SPEC_SESSION_KEYRING:
-		if (!cred->tgcred->session_keyring) {
+		if (!cred->session_keyring) {
 			/* always install a session keyring upon access if one
 			 * doesn't exist yet */
 			ret = install_user_keyrings();
@@ -597,7 +585,7 @@ try_again:
 			if (ret < 0)
 				goto error;
 			goto reget_creds;
-		} else if (cred->tgcred->session_keyring ==
+		} else if (cred->session_keyring ==
 			   cred->user->session_keyring &&
 			   lflags & KEY_LOOKUP_CREATE) {
 			ret = join_session_keyring(NULL);
@@ -607,7 +595,7 @@ try_again:
 		}
 
 		rcu_read_lock();
-		key = rcu_dereference(cred->tgcred->session_keyring);
+		key = rcu_dereference(cred->session_keyring);
 		atomic_inc(&key->usage);
 		rcu_read_unlock();
 		key_ref = make_key_ref(key, 1);
@@ -767,12 +755,6 @@ long join_session_keyring(const char *name)
 	struct key *keyring;
 	long ret, serial;
 
-	/* only permit this if there's a single thread in the thread group -
-	 * this avoids us having to adjust the creds on all threads and risking
-	 * ENOMEM */
-	if (!current_is_single_threaded())
-		return -EMLINK;
-
 	new = prepare_creds();
 	if (!new)
 		return -ENOMEM;
@@ -784,7 +766,7 @@ long join_session_keyring(const char *name)
 		if (ret < 0)
 			goto error;
 
-		serial = new->tgcred->session_keyring->serial;
+		serial = new->session_keyring->serial;
 		ret = commit_creds(new);
 		if (ret == 0)
 			ret = serial;
@@ -798,8 +780,10 @@ long join_session_keyring(const char *name)
 	keyring = find_keyring_by_name(name, false);
 	if (PTR_ERR(keyring) == -ENOKEY) {
 		/* not found - try and create a new one */
-		keyring = keyring_alloc(name, old->uid, old->gid, old,
-					KEY_ALLOC_IN_QUOTA, NULL);
+		keyring = keyring_alloc(
+			name, old->uid, old->gid, old,
+			KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_LINK,
+			KEY_ALLOC_IN_QUOTA, NULL);
 		if (IS_ERR(keyring)) {
 			ret = PTR_ERR(keyring);
 			goto error2;
@@ -807,6 +791,9 @@ long join_session_keyring(const char *name)
 	} else if (IS_ERR(keyring)) {
 		ret = PTR_ERR(keyring);
 		goto error2;
+	} else if (keyring == new->session_keyring) {
+		ret = 0;
+		goto error2;
 	}
 
 	/* we've got a keyring - now to install it */
@@ -863,8 +850,7 @@ void key_change_session_keyring(struct callback_head *twork)
 
 	new->jit_keyring	= old->jit_keyring;
 	new->thread_keyring	= key_get(old->thread_keyring);
-	new->tgcred->tgid	= old->tgcred->tgid;
-	new->tgcred->process_keyring = key_get(old->tgcred->process_keyring);
+	new->process_keyring	= key_get(old->process_keyring);
 
 	security_transfer_creds(new, old);
 
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 66e2118..4bd6bdb 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -126,6 +126,7 @@ static int call_sbin_request_key(struct key_construction *cons,
 
 	cred = get_current_cred();
 	keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
+				KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
 				KEY_ALLOC_QUOTA_OVERRUN, NULL);
 	put_cred(cred);
 	if (IS_ERR(keyring)) {
@@ -150,12 +151,12 @@ static int call_sbin_request_key(struct key_construction *cons,
 		cred->thread_keyring ? cred->thread_keyring->serial : 0);
 
 	prkey = 0;
-	if (cred->tgcred->process_keyring)
-		prkey = cred->tgcred->process_keyring->serial;
+	if (cred->process_keyring)
+		prkey = cred->process_keyring->serial;
 	sprintf(keyring_str[1], "%d", prkey);
 
 	rcu_read_lock();
-	session = rcu_dereference(cred->tgcred->session_keyring);
+	session = rcu_dereference(cred->session_keyring);
 	if (!session)
 		session = cred->user->session_keyring;
 	sskey = session->serial;
@@ -297,14 +298,14 @@ static void construct_get_dest_keyring(struct key **_dest_keyring)
 				break;
 
 		case KEY_REQKEY_DEFL_PROCESS_KEYRING:
-			dest_keyring = key_get(cred->tgcred->process_keyring);
+			dest_keyring = key_get(cred->process_keyring);
 			if (dest_keyring)
 				break;
 
 		case KEY_REQKEY_DEFL_SESSION_KEYRING:
 			rcu_read_lock();
 			dest_keyring = key_get(
-				rcu_dereference(cred->tgcred->session_keyring));
+				rcu_dereference(cred->session_keyring));
 			rcu_read_unlock();
 
 			if (dest_keyring)
@@ -347,6 +348,7 @@ static int construct_alloc_key(struct key_type *type,
 	const struct cred *cred = current_cred();
 	unsigned long prealloc;
 	struct key *key;
+	key_perm_t perm;
 	key_ref_t key_ref;
 	int ret;
 
@@ -355,8 +357,15 @@ static int construct_alloc_key(struct key_type *type,
 	*_key = NULL;
 	mutex_lock(&user->cons_lock);
 
+	perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
+	perm |= KEY_USR_VIEW;
+	if (type->read)
+		perm |= KEY_POS_READ;
+	if (type == &key_type_keyring || type->update)
+		perm |= KEY_POS_WRITE;
+
 	key = key_alloc(type, description, cred->fsuid, cred->fsgid, cred,
-			KEY_POS_ALL, flags);
+			perm, flags);
 	if (IS_ERR(key))
 		goto alloc_failed;
 
diff --git a/security/smack/Kconfig b/security/smack/Kconfig
index 603b087..e69de9c 100644
--- a/security/smack/Kconfig
+++ b/security/smack/Kconfig
@@ -1,6 +1,10 @@
 config SECURITY_SMACK
 	bool "Simplified Mandatory Access Control Kernel Support"
-	depends on NETLABEL && SECURITY_NETWORK
+	depends on NET
+	depends on INET
+	depends on SECURITY
+	select NETLABEL
+	select SECURITY_NETWORK
 	default n
 	help
 	  This selects the Simplified Mandatory Access Control Kernel.
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 99929a5..76a5dca 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -2063,6 +2063,19 @@ static const struct file_operations smk_revoke_subj_ops = {
 	.llseek		= generic_file_llseek,
 };
 
+static struct kset *smackfs_kset;
+/**
+ * smk_init_sysfs - initialize /sys/fs/smackfs
+ *
+ */
+static int smk_init_sysfs(void)
+{
+	smackfs_kset = kset_create_and_add("smackfs", NULL, fs_kobj);
+	if (!smackfs_kset)
+		return -ENOMEM;
+	return 0;
+}
+
 /**
  * smk_fill_super - fill the /smackfs superblock
  * @sb: the empty superblock
@@ -2183,6 +2196,10 @@ static int __init init_smk_fs(void)
 	if (!security_module_enable(&smack_ops))
 		return 0;
 
+	err = smk_init_sysfs();
+	if (err)
+		printk(KERN_ERR "smackfs: sysfs mountpoint problem.\n");
+
 	err = register_filesystem(&smk_fs_type);
 	if (!err) {
 		smackfs_mount = kern_mount(&smk_fs_type);
diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index b4c2984..2663145 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -17,6 +17,7 @@
 #include <linux/ptrace.h>
 #include <linux/prctl.h>
 #include <linux/ratelimit.h>
+#include <linux/workqueue.h>
 
 #define YAMA_SCOPE_DISABLED	0
 #define YAMA_SCOPE_RELATIONAL	1
@@ -29,12 +30,37 @@ static int ptrace_scope = YAMA_SCOPE_RELATIONAL;
 struct ptrace_relation {
 	struct task_struct *tracer;
 	struct task_struct *tracee;
+	bool invalid;
 	struct list_head node;
+	struct rcu_head rcu;
 };
 
 static LIST_HEAD(ptracer_relations);
 static DEFINE_SPINLOCK(ptracer_relations_lock);
 
+static void yama_relation_cleanup(struct work_struct *work);
+static DECLARE_WORK(yama_relation_work, yama_relation_cleanup);
+
+/**
+ * yama_relation_cleanup - remove invalid entries from the relation list
+ *
+ */
+static void yama_relation_cleanup(struct work_struct *work)
+{
+	struct ptrace_relation *relation;
+
+	spin_lock(&ptracer_relations_lock);
+	rcu_read_lock();
+	list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+		if (relation->invalid) {
+			list_del_rcu(&relation->node);
+			kfree_rcu(relation, rcu);
+		}
+	}
+	rcu_read_unlock();
+	spin_unlock(&ptracer_relations_lock);
+}
+
 /**
  * yama_ptracer_add - add/replace an exception for this tracer/tracee pair
  * @tracer: the task_struct of the process doing the ptrace
@@ -48,32 +74,34 @@ static DEFINE_SPINLOCK(ptracer_relations_lock);
 static int yama_ptracer_add(struct task_struct *tracer,
 			    struct task_struct *tracee)
 {
-	int rc = 0;
-	struct ptrace_relation *added;
-	struct ptrace_relation *entry, *relation = NULL;
+	struct ptrace_relation *relation, *added;
 
 	added = kmalloc(sizeof(*added), GFP_KERNEL);
 	if (!added)
 		return -ENOMEM;
 
-	spin_lock_bh(&ptracer_relations_lock);
-	list_for_each_entry(entry, &ptracer_relations, node)
-		if (entry->tracee == tracee) {
-			relation = entry;
-			break;
+	added->tracee = tracee;
+	added->tracer = tracer;
+	added->invalid = false;
+
+	spin_lock(&ptracer_relations_lock);
+	rcu_read_lock();
+	list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+		if (relation->invalid)
+			continue;
+		if (relation->tracee == tracee) {
+			list_replace_rcu(&relation->node, &added->node);
+			kfree_rcu(relation, rcu);
+			goto out;
 		}
-	if (!relation) {
-		relation = added;
-		relation->tracee = tracee;
-		list_add(&relation->node, &ptracer_relations);
 	}
-	relation->tracer = tracer;
 
-	spin_unlock_bh(&ptracer_relations_lock);
-	if (added != relation)
-		kfree(added);
+	list_add_rcu(&added->node, &ptracer_relations);
 
-	return rc;
+out:
+	rcu_read_unlock();
+	spin_unlock(&ptracer_relations_lock);
+	return 0;
 }
 
 /**
@@ -84,16 +112,23 @@ static int yama_ptracer_add(struct task_struct *tracer,
 static void yama_ptracer_del(struct task_struct *tracer,
 			     struct task_struct *tracee)
 {
-	struct ptrace_relation *relation, *safe;
+	struct ptrace_relation *relation;
+	bool marked = false;
 
-	spin_lock_bh(&ptracer_relations_lock);
-	list_for_each_entry_safe(relation, safe, &ptracer_relations, node)
+	rcu_read_lock();
+	list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+		if (relation->invalid)
+			continue;
 		if (relation->tracee == tracee ||
 		    (tracer && relation->tracer == tracer)) {
-			list_del(&relation->node);
-			kfree(relation);
+			relation->invalid = true;
+			marked = true;
 		}
-	spin_unlock_bh(&ptracer_relations_lock);
+	}
+	rcu_read_unlock();
+
+	if (marked)
+		schedule_work(&yama_relation_work);
 }
 
 /**
@@ -217,21 +252,22 @@ static int ptracer_exception_found(struct task_struct *tracer,
 	struct task_struct *parent = NULL;
 	bool found = false;
 
-	spin_lock_bh(&ptracer_relations_lock);
 	rcu_read_lock();
 	if (!thread_group_leader(tracee))
 		tracee = rcu_dereference(tracee->group_leader);
-	list_for_each_entry(relation, &ptracer_relations, node)
+	list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+		if (relation->invalid)
+			continue;
 		if (relation->tracee == tracee) {
 			parent = relation->tracer;
 			found = true;
 			break;
 		}
+	}
 
 	if (found && (parent == NULL || task_is_descendant(parent, tracer)))
 		rc = 1;
 	rcu_read_unlock();
-	spin_unlock_bh(&ptracer_relations_lock);
 
 	return rc;
 }