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Commit 28eefa75 authored by Ming Lei's avatar Ming Lei Committed by Greg Kroah-Hartman
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firmware loader: fix races during loading firmware 



This patch fixes two races in loading firmware:

1, FW_STATUS_DONE should be set before waking up the task waitting
on _request_firmware_load, otherwise FW_STATUS_ABORT may be
thought as DONE mistakenly.

2, Inside _request_firmware_load(), there is a small window between
wait_for_completion() and mutex_lock(&fw_lock), and 'echo 1 > loading'
still may happen during the period, so this patch checks FW_STATUS_DONE
to prevent pages' buffer completed from being freed in firmware_loading_store.

Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 65710cb6

drivers/base/firmware_class.c

+11 −9
Original line number Diff line number Diff line
@@ -243,6 +243,7 @@ static ssize_t firmware_loading_store(struct device *dev, 
	switch (loading) {

	case 1:

		/* discarding any previous partial load */

		if (!test_bit(FW_STATUS_DONE, &fw_priv->status)) {

			for (i = 0; i < fw_priv->nr_pages; i++)

				__free_page(fw_priv->pages[i]);

			kfree(fw_priv->pages);
@@ -250,11 +251,13 @@ static ssize_t firmware_loading_store(struct device *dev, 
			fw_priv->page_array_size = 0;

			fw_priv->nr_pages = 0;

			set_bit(FW_STATUS_LOADING, &fw_priv->status);

		}

		break;

	case 0:

		if (test_bit(FW_STATUS_LOADING, &fw_priv->status)) {

			complete(&fw_priv->completion);

			set_bit(FW_STATUS_DONE, &fw_priv->status);

			clear_bit(FW_STATUS_LOADING, &fw_priv->status);

			complete(&fw_priv->completion);

			break;

		}

		/* fallthrough */
@@ -557,7 +560,6 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent, 


	wait_for_completion(&fw_priv->completion);



	set_bit(FW_STATUS_DONE, &fw_priv->status);

	del_timer_sync(&fw_priv->timeout);



	mutex_lock(&fw_lock);