tpm: fix sleep-in-spinlock (8e39c933) · Commits · 戴 / test

flush_scheduled_work() can sleep, and we're calling it under spinlock. AFAICS, moving flush_scheduled_work before spin_lock() should not cause any problems. Reason being - The only thing that can race against tpm_release is tpm_open (tpm_release is called when last reference to the file is closed and only thing that can happen after that is tpm_open??) and tpm_open acquires driver_lock and more over it bails out with EBUSY if chip->num_opens is greater than 0. I also moved chip->num_pending-- to after deleting timer and setting data pending as it looks more correct for the paranoid although it probably doesn't matter as it is guarded by driver_lock. None the less this change should not cause problems. While I was at it I noticed a missing NULL check in tpm_register_hardware which is fixed with this patch as well. Signed-off-by:

Parag Warudkar <parag.warudkar@gmail.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/tpm/tpm.c

+8 −4

Original line number	Diff line number	Diff line
		@@ -942,12 +942,12 @@ int tpm_release(struct inode inode, struct file file)
		{
		struct tpm_chip *chip = file->private_data;

		flush_scheduled_work();
		spin_lock(&driver_lock);
		file->private_data = NULL;
		chip->num_opens--;
		del_singleshot_timer_sync(&chip->user_read_timer);
		flush_scheduled_work();
		atomic_set(&chip->data_pending, 0);
		chip->num_opens--;
		put_device(chip->dev);
		kfree(chip->data_buffer);
		spin_unlock(&driver_lock);
		@@ -1097,8 +1097,13 @@ struct tpm_chip tpm_register_hardware(struct device dev, const struct tpm_vend

		/* Driver specific per-device data */
		chip = kzalloc(sizeof(*chip), GFP_KERNEL);
		if (chip == NULL)
		devname = kmalloc(DEVNAME_SIZE, GFP_KERNEL);

		if (chip == NULL \|\| devname == NULL) {
		kfree(chip);
		kfree(devname);
		return NULL;
		}

		init_MUTEX(&chip->buffer_mutex);
		init_MUTEX(&chip->tpm_mutex);
		@@ -1124,7 +1129,6 @@ struct tpm_chip tpm_register_hardware(struct device dev, const struct tpm_vend

		set_bit(chip->dev_num, dev_mask);

		devname = kmalloc(DEVNAME_SIZE, GFP_KERNEL);
		scnprintf(devname, DEVNAME_SIZE, "%s%d", "tpm", chip->dev_num);
		chip->vendor.miscdev.name = devname;

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