[PATCH 5/6] Yama: fix default relationship to check thread group

[Paolo Pisati]

From: Kees Cook <kees at ubuntu.com>

Yet another case of a thread needing to match against the group leader.

BugLink: http://bugs.launchpad.net/bugs/737676
Signed-off-by: Kees Cook <kees.cook at canonical.com>
Signed-off-by: Andy Whitcroft <apw at canonical.com>
Acked-by: Brad Figg <brad.figg at canonical.com>
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
(cherry picked from commit 47208c22ade02f2b0b95dc3cb38e9a30c5ac600a)

BugLink: http://launchpad.net/bugs/893190

Signed-off-by: Paolo Pisati <paolo.pisati at canonical.com>
---
 security/yama/yama_lsm.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 1fb1f90..f3e7d7f 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -169,6 +169,8 @@ static int task_is_descendant(struct task_struct *parent,
 
 	rcu_read_lock();
 	read_lock(&tasklist_lock);
+	if (!thread_group_leader(parent))
+		parent = parent->group_leader;
 	while (walker->pid > 0) {
 		if (!thread_group_leader(walker))
 			walker = walker->group_leader;
-- 
1.7.5.4