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authorSchspa Shi <schspa@gmail.com>2022-05-08 18:02:47 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-05-12 19:34:58 +0300
commit5f0b5f4d50fa0faa8c76ef9d42a42e8d43f98b44 (patch)
tree66dd0a7db939d02324b6d32fbf2e0d54fd56af26 /drivers/usb
parent4031cd95cba70c72e4cadc2d46624bcd31e5a6c0 (diff)
downloadlinux-5f0b5f4d50fa0faa8c76ef9d42a42e8d43f98b44.tar.xz
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.c2
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);