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mISDN: fix mISDN_read()/mISDN_read() race
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
parent
1678ec00a6
commit
ebb06be16b
1 changed files with 14 additions and 9 deletions
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@ -102,36 +102,41 @@ static ssize_t
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mISDN_read(struct file *filep, char __user *buf, size_t count, loff_t *off)
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mISDN_read(struct file *filep, char __user *buf, size_t count, loff_t *off)
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{
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{
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struct mISDNtimerdev *dev = filep->private_data;
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struct mISDNtimerdev *dev = filep->private_data;
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struct list_head *list = &dev->expired;
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struct mISDNtimer *timer;
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struct mISDNtimer *timer;
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u_long flags;
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int ret = 0;
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int ret = 0;
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if (*debug & DEBUG_TIMER)
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if (*debug & DEBUG_TIMER)
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printk(KERN_DEBUG "%s(%p, %p, %d, %p)\n", __func__,
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printk(KERN_DEBUG "%s(%p, %p, %d, %p)\n", __func__,
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filep, buf, (int)count, off);
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filep, buf, (int)count, off);
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if (list_empty(&dev->expired) && (dev->work == 0)) {
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if (count < sizeof(int))
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return -ENOSPC;
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spin_lock_irq(&dev->lock);
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while (list_empty(list) && (dev->work == 0)) {
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spin_unlock_irq(&dev->lock);
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if (filep->f_flags & O_NONBLOCK)
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if (filep->f_flags & O_NONBLOCK)
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return -EAGAIN;
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return -EAGAIN;
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wait_event_interruptible(dev->wait, (dev->work ||
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wait_event_interruptible(dev->wait, (dev->work ||
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!list_empty(&dev->expired)));
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!list_empty(list)));
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if (signal_pending(current))
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if (signal_pending(current))
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return -ERESTARTSYS;
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return -ERESTARTSYS;
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spin_lock_irq(&dev->lock);
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}
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}
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if (count < sizeof(int))
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return -ENOSPC;
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if (dev->work)
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if (dev->work)
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dev->work = 0;
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dev->work = 0;
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if (!list_empty(&dev->expired)) {
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if (!list_empty(list)) {
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spin_lock_irqsave(&dev->lock, flags);
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timer = list_first_entry(list, struct mISDNtimer, list);
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timer = (struct mISDNtimer *)dev->expired.next;
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list_del(&timer->list);
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list_del(&timer->list);
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spin_unlock_irqrestore(&dev->lock, flags);
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spin_unlock_irq(&dev->lock);
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if (put_user(timer->id, (int __user *)buf))
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if (put_user(timer->id, (int __user *)buf))
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ret = -EFAULT;
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ret = -EFAULT;
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else
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else
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ret = sizeof(int);
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ret = sizeof(int);
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kfree(timer);
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kfree(timer);
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} else {
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spin_unlock_irq(&dev->lock);
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}
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}
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return ret;
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return ret;
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}
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}
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