On Sat, May 28, 2022 at 10:55:22AM -0700, syzbot wrote: > Hello, > > syzbot has tested the proposed patch and the reproducer did not trigger any issue: > > Reported-and-tested-by: syzbot+02b16343704b3af1667e@xxxxxxxxxxxxxxxxxxxxxxxxx > > Tested on: > > commit: 97fa5887 USB: new quirk for Dell Gen 2 devices > git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git > kernel config: https://syzkaller.appspot.com/x/.config?x=d7b232ec3adf5c8d > dashboard link: https://syzkaller.appspot.com/bug?extid=02b16343704b3af1667e > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > patch: https://syzkaller.appspot.com/x/patch.diff?x=10f44625f00000 > > Note: testing is done by a robot and is best-effort only. Yeah, I don't believe this result. In any case, I believe the second problem (unexpected unregistration) arises because the driver has no protection against multiple threads calling raw_ioctl_run() concurrently. Fixing that should be a second patch, but for testing purposes the two are combined below. Alan Stern #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git 97fa5887cf28 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 { @@ -145,6 +149,7 @@ 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 @@ -160,6 +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; @@ -188,6 +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; } @@ -198,6 +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); @@ -421,6 +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))) @@ -439,36 +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; } @@ -483,14 +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; } @@ -508,6 +539,7 @@ static int raw_ioctl_run(struct raw_dev ret = -EINVAL; goto out_unlock; } + dev->state = STATE_DEV_REGISTERING; spin_unlock_irqrestore(&dev->lock, flags); ret = usb_gadget_register_driver(&dev->driver);
