From: Corey Minyard cminyard@mvista.com
commit 3b9a907223d7f6b9d1dadea29436842ae9bcd76d upstream.
free_user() could be called in atomic context.
This patch pushed the free operation off into a workqueue.
Example:
BUG: sleeping function called from invalid context at kernel/workqueue.c:2856 in_atomic(): 1, irqs_disabled(): 0, pid: 177, name: ksoftirqd/27 CPU: 27 PID: 177 Comm: ksoftirqd/27 Not tainted 4.19.25-3 #1 Hardware name: AIC 1S-HV26-08/MB-DPSB04-06, BIOS IVYBV060 10/21/2015 Call Trace: dump_stack+0x5c/0x7b ___might_sleep+0xec/0x110 __flush_work+0x48/0x1f0 ? try_to_del_timer_sync+0x4d/0x80 _cleanup_srcu_struct+0x104/0x140 free_user+0x18/0x30 [ipmi_msghandler] ipmi_free_recv_msg+0x3a/0x50 [ipmi_msghandler] deliver_response+0xbd/0xd0 [ipmi_msghandler] deliver_local_response+0xe/0x30 [ipmi_msghandler] handle_one_recv_msg+0x163/0xc80 [ipmi_msghandler] ? dequeue_entity+0xa0/0x960 handle_new_recv_msgs+0x15c/0x1f0 [ipmi_msghandler] tasklet_action_common.isra.22+0x103/0x120 __do_softirq+0xf8/0x2d7 run_ksoftirqd+0x26/0x50 smpboot_thread_fn+0x11d/0x1e0 kthread+0x103/0x140 ? sort_range+0x20/0x20 ? kthread_destroy_worker+0x40/0x40 ret_from_fork+0x1f/0x40
Fixes: 77f8269606bf ("ipmi: fix use-after-free of user->release_barrier.rda")
Reported-by: Konstantin Khlebnikov khlebnikov@yandex-team.ru Signed-off-by: Corey Minyard cminyard@mvista.com Cc: stable@vger.kernel.org # 5.0 Cc: Yang Yingliang yangyingliang@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/char/ipmi/ipmi_msghandler.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-)
--- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -214,6 +214,9 @@ struct ipmi_user {
/* Does this interface receive IPMI events? */ bool gets_events; + + /* Free must run in process context for RCU cleanup. */ + struct work_struct remove_work; };
static struct ipmi_user *acquire_ipmi_user(struct ipmi_user *user, int *index) @@ -1079,6 +1082,15 @@ static int intf_err_seq(struct ipmi_smi }
+static void free_user_work(struct work_struct *work) +{ + struct ipmi_user *user = container_of(work, struct ipmi_user, + remove_work); + + cleanup_srcu_struct(&user->release_barrier); + kfree(user); +} + int ipmi_create_user(unsigned int if_num, const struct ipmi_user_hndl *handler, void *handler_data, @@ -1122,6 +1134,8 @@ int ipmi_create_user(unsigned int goto out_kfree;
found: + INIT_WORK(&new_user->remove_work, free_user_work); + rv = init_srcu_struct(&new_user->release_barrier); if (rv) goto out_kfree; @@ -1184,8 +1198,9 @@ EXPORT_SYMBOL(ipmi_get_smi_info); static void free_user(struct kref *ref) { struct ipmi_user *user = container_of(ref, struct ipmi_user, refcount); - cleanup_srcu_struct(&user->release_barrier); - kfree(user); + + /* SRCU cleanup must happen in task context. */ + schedule_work(&user->remove_work); }
static void _ipmi_destroy_user(struct ipmi_user *user)