===================================================================
@@ -682,16 +682,21 @@ static int usbhid_open(struct hid_device
struct usbhid_device *usbhid = hid->driver_data;
int res;
+ mutex_lock(&usbhid->mutex);
+
set_bit(HID_OPENED, &usbhid->iofl);
- if (hid->quirks & HID_QUIRK_ALWAYS_POLL)
- return 0;
+ if (hid->quirks & HID_QUIRK_ALWAYS_POLL) {
+ res = 0;
+ goto Done;
+ }
res = usb_autopm_get_interface(usbhid->intf);
/* the device must be awake to reliably request remote wakeup */
if (res < 0) {
clear_bit(HID_OPENED, &usbhid->iofl);
- return -EIO;
+ res = -EIO;
+ goto Done;
}
usbhid->intf->needs_remote_wakeup = 1;
@@ -725,6 +730,9 @@ static int usbhid_open(struct hid_device
msleep(50);
clear_bit(HID_RESUME_RUNNING, &usbhid->iofl);
+
+ Done:
+ mutex_unlock(&usbhid->mutex);
return res;
}
@@ -732,6 +740,8 @@ static void usbhid_close(struct hid_devi
{
struct usbhid_device *usbhid = hid->driver_data;
+ mutex_lock(&usbhid->mutex);
+
/*
* Make sure we don't restart data acquisition due to
* a resumption we no longer care about by avoiding racing
@@ -743,12 +753,13 @@ static void usbhid_close(struct hid_devi
clear_bit(HID_IN_POLLING, &usbhid->iofl);
spin_unlock_irq(&usbhid->lock);
- if (hid->quirks & HID_QUIRK_ALWAYS_POLL)
- return;
+ if (!(hid->quirks & HID_QUIRK_ALWAYS_POLL)) {
+ hid_cancel_delayed_stuff(usbhid);
+ usb_kill_urb(usbhid->urbin);
+ usbhid->intf->needs_remote_wakeup = 0;
+ }
- hid_cancel_delayed_stuff(usbhid);
- usb_kill_urb(usbhid->urbin);
- usbhid->intf->needs_remote_wakeup = 0;
+ mutex_unlock(&usbhid->mutex);
}
/*
@@ -1057,6 +1068,8 @@ static int usbhid_start(struct hid_devic
unsigned int n, insize = 0;
int ret;
+ mutex_lock(&usbhid->mutex);
+
clear_bit(HID_DISCONNECTED, &usbhid->iofl);
usbhid->bufsize = HID_MIN_BUFFER_SIZE;
@@ -1177,6 +1190,8 @@ static int usbhid_start(struct hid_devic
usbhid_set_leds(hid);
device_set_wakeup_enable(&dev->dev, 1);
}
+
+ mutex_unlock(&usbhid->mutex);
return 0;
fail:
@@ -1187,6 +1202,7 @@ fail:
usbhid->urbout = NULL;
usbhid->urbctrl = NULL;
hid_free_buffers(dev, hid);
+ mutex_unlock(&usbhid->mutex);
return ret;
}
@@ -1202,6 +1218,8 @@ static void usbhid_stop(struct hid_devic
usbhid->intf->needs_remote_wakeup = 0;
}
+ mutex_lock(&usbhid->mutex);
+
clear_bit(HID_STARTED, &usbhid->iofl);
spin_lock_irq(&usbhid->lock); /* Sync with error and led handlers */
set_bit(HID_DISCONNECTED, &usbhid->iofl);
@@ -1222,6 +1240,8 @@ static void usbhid_stop(struct hid_devic
usbhid->urbout = NULL;
hid_free_buffers(hid_to_usb_dev(hid), hid);
+
+ mutex_unlock(&usbhid->mutex);
}
static int usbhid_power(struct hid_device *hid, int lvl)
@@ -1382,6 +1402,7 @@ static int usbhid_probe(struct usb_inter
INIT_WORK(&usbhid->reset_work, hid_reset);
timer_setup(&usbhid->io_retry, hid_retry_timeout, 0);
spin_lock_init(&usbhid->lock);
+ mutex_init(&usbhid->mutex);
ret = hid_add_device(hid);
if (ret) {
===================================================================
@@ -80,6 +80,7 @@ struct usbhid_device {
dma_addr_t outbuf_dma; /* Output buffer dma */
unsigned long last_out; /* record of last output for timeouts */
+ struct mutex mutex; /* start/stop/open/close */
spinlock_t lock; /* fifo spinlock */
unsigned long iofl; /* I/O flags (CTRL_RUNNING, OUT_RUNNING) */
struct timer_list io_retry; /* Retry timer */
The syzbot fuzzer discovered a bad race between in the usbhid driver between usbhid_stop() and usbhid_close(). In particular, usbhid_stop() does: usb_free_urb(usbhid->urbin); ... usbhid->urbin = NULL; /* don't mess up next start */ and usbhid_close() does: usb_kill_urb(usbhid->urbin); with no mutual exclusion. If the two routines happen to run concurrently so that usb_kill_urb() is called in between the usb_free_urb() and the NULL assignment, it will access the deallocated urb structure -- a use-after-free bug. This patch adds a mutex to the usbhid private structure and uses it to enforce mutual exclusion of the usbhid_start(), usbhid_stop(), usbhid_open() and usbhid_close() callbacks. Reported-and-tested-by: syzbot+7bf5a7b0f0a1f9446f4c@syzkaller.appspotmail.com Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: <stable@vger.kernel.org> --- [as1935] drivers/hid/usbhid/hid-core.c | 37 +++++++++++++++++++++++++++++-------- drivers/hid/usbhid/usbhid.h | 1 + 2 files changed, 30 insertions(+), 8 deletions(-)