Commit 28eefa75 authored by Ming Lei's avatar Ming Lei Committed by Greg Kroah-Hartman

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
......@@ -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);
......
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