In a report for a separate bug (which has already been fixed by commit 5f0b5f4d50fa "usb: gadget: fix race when gadget driver register via ioctl") in the raw-gadget driver, the syzbot console log included error messages caused by attempted registration of a new driver with the same name as an existing driver: > kobject_add_internal failed for raw-gadget with -EEXIST, don't try to register things with the same name in the same directory. > UDC core: USB Raw Gadget: driver registration failed: -17 > misc raw-gadget: fail, usb_gadget_register_driver returned -17 These errors arise because raw_gadget.c registers a separate UDC driver for each of the UDC instances it creates, but these drivers all have the same name: "raw-gadget". Until recently this wasn't a problem, but when the "gadget" bus was added and UDC drivers were registered on this bus, it became possible for name conflicts to cause the registrations to fail. The reason is simply that the bus code in the driver core uses the driver name as a sysfs directory name (e.g., /sys/bus/gadget/drivers/raw-gadget/), and you can't create two directories with the same pathname. To fix this problem, the driver names used by raw-gadget are made distinct by appending a unique ID number: "raw-gadget.N", with a different value of N for each driver instance. And to avoid the proliferation of error handling code in the raw_ioctl_init() routine, the error return paths are refactored into the common pattern (goto statements leading to cleanup code at the end of the routine). Reported-and-tested-by: syzbot+02b16343704b3af1667e@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Acked-by: Hillf Danton <hdanton@xxxxxxxx> CC: Andrey Konovalov <andreyknvl@xxxxxxxxx> CC: <stable@xxxxxxxxxxxxxxx> Fixes: fc274c1e9973 "USB: gadget: Add a new bus for gadgets" Link: https://lore.kernel.org/all/0000000000008c664105dffae2eb@xxxxxxxxxx/ --- [as1981] drivers/usb/gadget/legacy/raw_gadget.c | 62 ++++++++++++++++++++++++--------- 1 file changed, 46 insertions(+), 16 deletions(-) Index: usb-devel/drivers/usb/gadget/legacy/raw_gadget.c =================================================================== --- usb-devel.orig/drivers/usb/gadget/legacy/raw_gadget.c +++ usb-devel/drivers/usb/gadget/legacy/raw_gadget.c @@ -11,6 +11,7 @@ #include <linux/ctype.h> #include <linux/debugfs.h> #include <linux/delay.h> +#include <linux/idr.h> #include <linux/kref.h> #include <linux/miscdevice.h> #include <linux/module.h> @@ -36,6 +37,9 @@ MODULE_LICENSE("GPL"); /*----------------------------------------------------------------------*/ +static DEFINE_IDA(driver_id_numbers); +#define DRIVER_DRIVER_NAME_LENGTH_MAX 32 + #define RAW_EVENT_QUEUE_SIZE 16 struct raw_event_queue { @@ -161,6 +165,9 @@ struct raw_dev { /* Reference to misc device: */ struct device *dev; + /* Make driver names unique */ + int driver_id_number; + /* Protected by lock: */ enum dev_state state; bool gadget_registered; @@ -189,6 +196,7 @@ static struct raw_dev *dev_new(void) spin_lock_init(&dev->lock); init_completion(&dev->ep0_done); raw_event_queue_init(&dev->queue); + dev->driver_id_number = -1; return dev; } @@ -199,6 +207,9 @@ static void dev_free(struct kref *kref) kfree(dev->udc_name); kfree(dev->driver.udc_name); + kfree(dev->driver.driver.name); + if (dev->driver_id_number >= 0) + ida_free(&driver_id_numbers, dev->driver_id_number); if (dev->req) { if (dev->ep0_urb_queued) usb_ep_dequeue(dev->gadget->ep0, dev->req); @@ -422,6 +433,7 @@ static int raw_ioctl_init(struct raw_dev struct usb_raw_init arg; char *udc_driver_name; char *udc_device_name; + char *driver_driver_name; unsigned long flags; if (copy_from_user(&arg, (void __user *)value, sizeof(arg))) @@ -440,36 +452,44 @@ static int raw_ioctl_init(struct raw_dev return -EINVAL; } + ret = ida_alloc(&driver_id_numbers, GFP_KERNEL); + if (ret < 0) + return ret; + dev->driver_id_number = ret; + + driver_driver_name = kmalloc(DRIVER_DRIVER_NAME_LENGTH_MAX, GFP_KERNEL); + if (!driver_driver_name) { + ret = -ENOMEM; + goto out_free_driver_id_number; + } + snprintf(driver_driver_name, DRIVER_DRIVER_NAME_LENGTH_MAX, + DRIVER_NAME ".%d", dev->driver_id_number); + udc_driver_name = kmalloc(UDC_NAME_LENGTH_MAX, GFP_KERNEL); - if (!udc_driver_name) - return -ENOMEM; + if (!udc_driver_name) { + ret = -ENOMEM; + goto out_free_driver_driver_name; + } ret = strscpy(udc_driver_name, &arg.driver_name[0], UDC_NAME_LENGTH_MAX); - if (ret < 0) { - kfree(udc_driver_name); - return ret; - } + if (ret < 0) + goto out_free_udc_driver_name; ret = 0; udc_device_name = kmalloc(UDC_NAME_LENGTH_MAX, GFP_KERNEL); if (!udc_device_name) { - kfree(udc_driver_name); - return -ENOMEM; + ret = -ENOMEM; + goto out_free_udc_driver_name; } ret = strscpy(udc_device_name, &arg.device_name[0], UDC_NAME_LENGTH_MAX); - if (ret < 0) { - kfree(udc_driver_name); - kfree(udc_device_name); - return ret; - } + if (ret < 0) + goto out_free_udc_device_name; ret = 0; spin_lock_irqsave(&dev->lock, flags); if (dev->state != STATE_DEV_OPENED) { dev_dbg(dev->dev, "fail, device is not opened\n"); - kfree(udc_driver_name); - kfree(udc_device_name); ret = -EINVAL; goto out_unlock; } @@ -484,14 +504,24 @@ static int raw_ioctl_init(struct raw_dev dev->driver.suspend = gadget_suspend; dev->driver.resume = gadget_resume; dev->driver.reset = gadget_reset; - dev->driver.driver.name = DRIVER_NAME; + dev->driver.driver.name = driver_driver_name; dev->driver.udc_name = udc_device_name; dev->driver.match_existing_only = 1; dev->state = STATE_DEV_INITIALIZED; + spin_unlock_irqrestore(&dev->lock, flags); + return ret; out_unlock: spin_unlock_irqrestore(&dev->lock, flags); +out_free_udc_device_name: + kfree(udc_device_name); +out_free_udc_driver_name: + kfree(udc_driver_name); +out_free_driver_driver_name: + kfree(driver_driver_name); +out_free_driver_id_number: + ida_free(&driver_id_numbers, dev->driver_id_number); return ret; }
