From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Gerald Schaefer , Peter Zijlstra , Ingo Molnar , Preeti U Murthy Subject: [PATCH 3.10 22/22] sched/autogroup: Fix race with task_groups list Date: Fri, 28 Mar 2014 10:32:14 -0700 Message-Id: <20140328173112.401929561@linuxfoundation.org> In-Reply-To: <20140328173109.378288825@linuxfoundation.org> References: <20140328173109.378288825@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gerald Schaefer commit 41261b6a832ea0e788627f6a8707854423f9ff49 upstream. In autogroup_create(), a tg is allocated and added to the task_groups list. If CONFIG_RT_GROUP_SCHED is set, this tg is then modified while on the list, without locking. This can race with someone walking the list, like __enable_runtime() during CPU unplug, and result in a use-after-free bug. To fix this, move sched_online_group(), which adds the tg to the list, to the end of the autogroup_create() function after the modification. Signed-off-by: Gerald Schaefer Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1369411669-46971-2-git-send-email-gerald.schaefer@de.ibm.com Signed-off-by: Ingo Molnar Signed-off-by: Preeti U Murthy Signed-off-by: Greg Kroah-Hartman --- kernel/sched/auto_group.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/kernel/sched/auto_group.c +++ b/kernel/sched/auto_group.c @@ -77,8 +77,6 @@ static inline struct autogroup *autogrou if (IS_ERR(tg)) goto out_free; - sched_online_group(tg, &root_task_group); - kref_init(&ag->kref); init_rwsem(&ag->lock); ag->id = atomic_inc_return(&autogroup_seq_nr); @@ -98,6 +96,7 @@ static inline struct autogroup *autogrou #endif tg->autogroup = ag; + sched_online_group(tg, &root_task_group); return ag; out_free: