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Subject[PATCH 5.0 083/115] ipmi: fix sleep-in-atomic in free_user at cleanup SRCU user->release_barrier
Date
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)

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