diff options
| author | Schspa Shi <schspa@gmail.com> | 2022-05-08 23:02:47 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-05-12 18:34:58 +0200 |
| commit | 5f0b5f4d50fa0faa8c76ef9d42a42e8d43f98b44 (patch) | |
| tree | 66dd0a7db939d02324b6d32fbf2e0d54fd56af26 /drivers/usb | |
| parent | 4031cd95cba70c72e4cadc2d46624bcd31e5a6c0 (diff) | |
| download | linux-5f0b5f4d50fa0faa8c76ef9d42a42e8d43f98b44.tar.gz | |
usb: gadget: fix race when gadget driver register via ioctl
The usb_gadget_register_driver can be called multi time by to
threads via USB_RAW_IOCTL_RUN ioctl syscall, which will lead
to multiple registrations.
Call trace:
driver_register+0x220/0x3a0 drivers/base/driver.c:171
usb_gadget_register_driver_owner+0xfb/0x1e0
drivers/usb/gadget/udc/core.c:1546
raw_ioctl_run drivers/usb/gadget/legacy/raw_gadget.c:513 [inline]
raw_ioctl+0x1883/0x2730 drivers/usb/gadget/legacy/raw_gadget.c:1220
ioctl USB_RAW_IOCTL_RUN
This routine allows two processes to register the same driver instance
via ioctl syscall. which lead to a race condition.
Please refer to the following scenarios.
T1 T2
------------------------------------------------------------------
usb_gadget_register_driver_owner
driver_register driver_register
driver_find driver_find
bus_add_driver bus_add_driver
priv alloced <context switch>
drv->p = priv;
<schedule out>
kobject_init_and_add // refcount = 1;
//couldn't find an available UDC or it's busy
<context switch>
priv alloced
drv->priv = priv;
kobject_init_and_add
---> refcount = 1 <------
// register success
<context switch>
===================== another ioctl/process ======================
driver_register
driver_find
k = kset_find_obj()
---> refcount = 2 <------
<context out>
driver_unregister
// drv->p become T2's priv
---> refcount = 1 <------
<context switch>
kobject_put(k)
---> refcount = 0 <------
return priv->driver;
--------UAF here----------
There will be UAF in this scenario.
We can fix it by adding a new STATE_DEV_REGISTERING device state to
avoid double register.
Reported-by: syzbot+dc7c3ca638e773db07f6@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/000000000000e66c2805de55b15a@google.com/
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Schspa Shi <schspa@gmail.com>
Link: https://lore.kernel.org/r/20220508150247.38204-1-schspa@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb')
| -rw-r--r-- | drivers/usb/gadget/legacy/raw_gadget.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/usb/gadget/legacy/raw_gadget.c b/drivers/usb/gadget/legacy/raw_gadget.c index 8d40a1f2ec57..e9440f7bf019 100644 --- a/drivers/usb/gadget/legacy/raw_gadget.c +++ b/drivers/usb/gadget/legacy/raw_gadget.c @@ -145,6 +145,7 @@ enum dev_state { STATE_DEV_INVALID = 0, STATE_DEV_OPENED, STATE_DEV_INITIALIZED, + STATE_DEV_REGISTERING, STATE_DEV_RUNNING, STATE_DEV_CLOSED, STATE_DEV_FAILED @@ -508,6 +509,7 @@ static int raw_ioctl_run(struct raw_dev *dev, unsigned long value) ret = -EINVAL; goto out_unlock; } + dev->state = STATE_DEV_REGISTERING; spin_unlock_irqrestore(&dev->lock, flags); ret = usb_gadget_probe_driver(&dev->driver); |