This is a note to let you know that I've just added the patch titled HID: usbhid: Fix race between usbhid_close() and usbhid_stop() to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: hid-usbhid-fix-race-between-usbhid_close-and-usbhid_stop.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 0ed08faded1da03eb3def61502b27f81aef2e615 Mon Sep 17 00:00:00 2001 From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Date: Wed, 22 Apr 2020 16:18:48 -0400 Subject: HID: usbhid: Fix race between usbhid_close() and usbhid_stop() From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> commit 0ed08faded1da03eb3def61502b27f81aef2e615 upstream. 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@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> CC: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Jiri Kosina <jkosina@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/hid/usbhid/hid-core.c | 37 +++++++++++++++++++++++++++++-------- drivers/hid/usbhid/usbhid.h | 1 + 2 files changed, 30 insertions(+), 8 deletions(-) --- a/drivers/hid/usbhid/hid-core.c +++ b/drivers/hid/usbhid/hid-core.c @@ -680,16 +680,21 @@ 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; @@ -723,6 +728,9 @@ static int usbhid_open(struct hid_device msleep(50); clear_bit(HID_RESUME_RUNNING, &usbhid->iofl); + + Done: + mutex_unlock(&usbhid->mutex); return res; } @@ -730,6 +738,8 @@ 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 @@ -741,12 +751,13 @@ 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); } /* @@ -1056,6 +1067,8 @@ 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; @@ -1170,6 +1183,8 @@ 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: @@ -1180,6 +1195,7 @@ fail: usbhid->urbout = NULL; usbhid->urbctrl = NULL; hid_free_buffers(dev, hid); + mutex_unlock(&usbhid->mutex); return ret; } @@ -1195,6 +1211,8 @@ 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); @@ -1215,6 +1233,8 @@ 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) @@ -1375,6 +1395,7 @@ static int usbhid_probe(struct usb_inter INIT_WORK(&usbhid->reset_work, hid_reset); setup_timer(&usbhid->io_retry, hid_retry_timeout, (unsigned long) hid); spin_lock_init(&usbhid->lock); + mutex_init(&usbhid->mutex); ret = hid_add_device(hid); if (ret) { --- a/drivers/hid/usbhid/usbhid.h +++ b/drivers/hid/usbhid/usbhid.h @@ -93,6 +93,7 @@ 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 */ Patches currently in stable-queue which might be from stern@xxxxxxxxxxxxxxxxxxx are queue-4.14/hid-usbhid-fix-race-between-usbhid_close-and-usbhid_stop.patch