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[media] dvb_frontend: move kref to struct dvb_frontend

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This commit amends my old commit fe35637b0a9f ("[media] dvb_frontend:
eliminate blocking wait in dvb_unregister_frontend()"), which added
kref to struct dvb_frontend_private.  It turned out that there are
several use-after-free bugs left, which affect the struct
dvb_frontend.  Protecting it with kref also protects struct
dvb_frontend_private, so we can simply move it.

This is how the use-after-free looks like in KASAN:

    BUG: KASAN: use-after-free in string+0x60/0xb1 at addr ffff880033bd9fc0
    Read of size 1 by task kworker/0:2/617
    CPU: 0 PID: 617 Comm: kworker/0:2 Not tainted 4.8.0-rc1-hosting+ #60
    Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
    Workqueue: usb_hub_wq hub_event
     0000000000000000 ffff880033757218 ffffffff81394e50 ffff880033bd9fd0
     ffff880035c03b00 ffff880033757240 ffffffff811f271d ffff880033bd9fc0
     1ffff1000677b3f8 ffffed000677b3f8 ffff8800337572b8 ffffffff811f2afe
    Call Trace:
     [...]
     [<ffffffff813a2d2f>] vsnprintf+0x39d/0x7e9
     [<ffffffff813993f9>] add_uevent_var+0x10f/0x1dc
     [<ffffffff814fe5ca>] rc_dev_uevent+0x55/0x6f
     [<ffffffff814438f8>] dev_uevent+0x2e1/0x316
     [<ffffffff81399744>] kobject_uevent_env+0x27e/0x701
     [<ffffffff81399bd2>] kobject_uevent+0xb/0xd
     [<ffffffff81443445>] device_del+0x322/0x383
     [<ffffffff81500c0c>] rc_unregister_device+0x98/0xc3
     [<ffffffff81508fb4>] dvb_usb_remote_exit+0x7a/0x90
     [<ffffffff81506157>] dvb_usb_exit+0x1d/0xe5
     [<ffffffff81506e90>] dvb_usb_device_exit+0x69/0x7d
     [<ffffffff8150a181>] pctv452e_usb_disconnect+0x7b/0x80
     [...]
    Object at ffff880033bd9fc0, in cache kmalloc-16 size: 16
    Allocated:
     [...]
    Freed:
    PID = 617
     [...]
     [<ffffffff811f034c>] kfree+0xd9/0x166
     [<ffffffff814fe513>] ir_free_table+0x2f/0x51
     [<ffffffff81500bc1>] rc_unregister_device+0x4d/0xc3
     [<ffffffff81508fb4>] dvb_usb_remote_exit+0x7a/0x90
     [<ffffffff81506157>] dvb_usb_exit+0x1d/0xe5
     [<ffffffff81506e90>] dvb_usb_device_exit+0x69/0x7d
     [<ffffffff8150a181>] pctv452e_usb_disconnect+0x7b/0x80

Another one:

    BUG: KASAN: use-after-free in do_sys_poll+0x336/0x6b8 at addr ffff88003563fcc0
    Read of size 8 by task tuner on fronte/1042
    CPU: 1 PID: 1042 Comm: tuner on fronte Tainted: G    B           4.8.0-rc1-hosting+ #60
    Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
     0000000000000000 ffff88003353f910 ffffffff81394e50 ffff88003563fd80
     ffff880035c03200 ffff88003353f938 ffffffff811f271d ffff88003563fc80
     1ffff10006ac7f98 ffffed0006ac7f98 ffff88003353f9b0 ffffffff811f2afe
    Call Trace:
     [...]
     [<ffffffff812289b3>] do_sys_poll+0x336/0x6b8
     [...]
     [<ffffffff81228ed9>] SyS_poll+0xa9/0x194
     [...]
    Object at ffff88003563fc80, in cache kmalloc-256 size: 256
    Allocated:
     [...]
    Freed:
    PID = 617
     [...]
     [<ffffffff811f034c>] kfree+0xd9/0x166
     [<ffffffff814eb60d>] dvb_unregister_device+0xd6/0xe5
     [<ffffffff814fa4ed>] dvb_unregister_frontend+0x4b/0x66
     [<ffffffff8150810b>] dvb_usb_adapter_frontend_exit+0x69/0xac
     [<ffffffff8150617d>] dvb_usb_exit+0x43/0xe5
     [<ffffffff81506e90>] dvb_usb_device_exit+0x69/0x7d
     [<ffffffff8150a181>] pctv452e_usb_disconnect+0x7b/0x80

Signed-off-by: Max Kellermann <max.kellermann@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Max Kellermann 2016-08-09 18:32:51 -03:00 committed by Mauro Carvalho Chehab
parent f686c14364
commit 1f862a68df
2 changed files with 31 additions and 16 deletions
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46
drivers/media/dvb-core/dvb_frontend.c
View File

@ -104,8 +104,6 @@ MODULE_PARM_DESC(dvb_mfe_wait_time, "Wait up to <mfe_wait_time> seconds on open(
static DEFINE_MUTEX(frontend_mutex);
struct dvb_frontend_private {
struct kref refcount;
/* thread/frontend values */
struct dvb_device *dvbdev;
struct dvb_frontend_parameters parameters_out;
@ -143,21 +141,30 @@ struct dvb_frontend_private {
#endif
};
static void dvb_frontend_private_free(struct kref *ref)
static void dvb_frontend_invoke_release(struct dvb_frontend *fe,
void (*release)(struct dvb_frontend *fe));
static void dvb_frontend_free(struct kref *ref)
{
struct dvb_frontend_private *fepriv =
container_of(ref, struct dvb_frontend_private, refcount);
struct dvb_frontend *fe =
container_of(ref, struct dvb_frontend, refcount);
struct dvb_frontend_private *fepriv = fe->frontend_priv;
dvb_free_device(fepriv->dvbdev);
dvb_frontend_invoke_release(fe, fe->ops.release);
kfree(fepriv);
}
static void dvb_frontend_private_put(struct dvb_frontend_private *fepriv)
static void dvb_frontend_put(struct dvb_frontend *fe)
{
kref_put(&fepriv->refcount, dvb_frontend_private_free);
kref_put(&fe->refcount, dvb_frontend_free);
}
static void dvb_frontend_private_get(struct dvb_frontend_private *fepriv)
static void dvb_frontend_get(struct dvb_frontend *fe)
{
kref_get(&fepriv->refcount);
kref_get(&fe->refcount);
}
static void dvb_frontend_wakeup(struct dvb_frontend *fe);
@ -2555,7 +2562,7 @@ static int dvb_frontend_open(struct inode *inode, struct file *file)
fepriv->events.eventr = fepriv->events.eventw = 0;
}
dvb_frontend_private_get(fepriv);
dvb_frontend_get(fe);
if (adapter->mfe_shared)
mutex_unlock (&adapter->mfe_lock);
@ -2605,7 +2612,7 @@ static int dvb_frontend_release(struct inode *inode, struct file *file)
fe->ops.ts_bus_ctrl(fe, 0);
}
dvb_frontend_private_put(fepriv);
dvb_frontend_put(fe);
return ret;
}
@ -2695,7 +2702,14 @@ int dvb_register_frontend(struct dvb_adapter* dvb,
}
fepriv = fe->frontend_priv;
kref_init(&fepriv->refcount);
kref_init(&fe->refcount);
/*
* After initialization, there need to be two references: one
* for dvb_unregister_frontend(), and another one for
* dvb_frontend_detach().
*/
dvb_frontend_get(fe);
sema_init(&fepriv->sem, 1);
init_waitqueue_head (&fepriv->wait_queue);
@ -2730,12 +2744,12 @@ int dvb_unregister_frontend(struct dvb_frontend* fe)
dev_dbg(fe->dvb->device, "%s:\n", __func__);
mutex_lock(&frontend_mutex);
dvb_frontend_stop (fe);
dvb_unregister_device (fepriv->dvbdev);
dvb_frontend_stop(fe);
dvb_remove_device(fepriv->dvbdev);
/* fe is invalid now */
mutex_unlock(&frontend_mutex);
dvb_frontend_private_put(fepriv);
dvb_frontend_put(fe);
return 0;
}
EXPORT_SYMBOL(dvb_unregister_frontend);
@ -2757,6 +2771,6 @@ void dvb_frontend_detach(struct dvb_frontend* fe)
dvb_frontend_invoke_release(fe, fe->ops.tuner_ops.release);
dvb_frontend_invoke_release(fe, fe->ops.analog_ops.release);
dvb_frontend_invoke_release(fe, fe->ops.detach);
dvb_frontend_invoke_release(fe, fe->ops.release);
dvb_frontend_put(fe);
}
EXPORT_SYMBOL(dvb_frontend_detach);

1
drivers/media/dvb-core/dvb_frontend.h
View File

@ -667,6 +667,7 @@ struct dtv_frontend_properties {
*/
struct dvb_frontend {
struct kref refcount;
struct dvb_frontend_ops ops;
struct dvb_adapter *dvb;
void *demodulator_priv;