Calls to usb_kill_anchored_urbs() after usb_kill_urb() on multiprocessor systems create a race condition in which usb_kill_anchored_urbs() deallocates the URB before the completer callback is called in usb_kill_urb(), resulting in a use-after-free. To fix this, add proper lock protection to usb_kill_urb() calls that can possibly run concurrently with usb_kill_anchored_urbs(). Reported-by: syzbot+89bd486af9427a9fc605@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://syzkaller.appspot.com/bug?id=cabffad18eb74197f84871802fd2c5117b61febf Signed-off-by: Brooke Basile <brookebasile@xxxxxxxxx> --- drivers/net/wireless/ath/ath9k/hif_usb.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c index 3f563e02d17d..2ed98aaed6fb 100644 --- a/drivers/net/wireless/ath/ath9k/hif_usb.c +++ b/drivers/net/wireless/ath/ath9k/hif_usb.c @@ -449,10 +449,19 @@ static void hif_usb_stop(void *hif_handle) spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags); /* The pending URBs have to be canceled. */ + spin_lock_irqsave(&hif_dev->tx.tx_lock, flags); list_for_each_entry_safe(tx_buf, tx_buf_tmp, &hif_dev->tx.tx_pending, list) { + usb_get_urb(tx_buf->urb); + spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags); usb_kill_urb(tx_buf->urb); + list_del(&tx_buf->list); + usb_free_urb(tx_buf->urb); + kfree(tx_buf->buf); + kfree(tx_buf); + spin_lock_irqsave(&hif_dev->tx.tx_lock, flags); } + spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags); usb_kill_anchored_urbs(&hif_dev->mgmt_submitted); } @@ -762,27 +771,37 @@ static void ath9k_hif_usb_dealloc_tx_urbs(struct hif_device_usb *hif_dev) struct tx_buf *tx_buf = NULL, *tx_buf_tmp = NULL; unsigned long flags; + spin_lock_irqsave(&hif_dev->tx.tx_lock, flags); list_for_each_entry_safe(tx_buf, tx_buf_tmp, &hif_dev->tx.tx_buf, list) { + usb_get_urb(tx_buf->urb); + spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags); usb_kill_urb(tx_buf->urb); list_del(&tx_buf->list); usb_free_urb(tx_buf->urb); kfree(tx_buf->buf); kfree(tx_buf); + spin_lock_irqsave(&hif_dev->tx.tx_lock, flags); } + spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags); spin_lock_irqsave(&hif_dev->tx.tx_lock, flags); hif_dev->tx.flags |= HIF_USB_TX_FLUSH; spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags); + spin_lock_irqsave(&hif_dev->tx.tx_lock, flags); list_for_each_entry_safe(tx_buf, tx_buf_tmp, &hif_dev->tx.tx_pending, list) { + usb_get_urb(tx_buf->urb); + spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags); usb_kill_urb(tx_buf->urb); list_del(&tx_buf->list); usb_free_urb(tx_buf->urb); kfree(tx_buf->buf); kfree(tx_buf); + spin_lock_irqsave(&hif_dev->tx.tx_lock, flags); } + spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags); usb_kill_anchored_urbs(&hif_dev->mgmt_submitted); } -- 2.28.0
