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authorMing Lei <ming.lei@canonical.com>2012-08-04 12:01:17 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-08-16 13:13:18 -0700
commit28eefa750b5e16b13bb869c2c4f7d624a43eb48b (patch)
tree1bf6575f9884bdb49f9b8340d159b5ced97383e2 /drivers/base/firmware_class.c
parent65710cb6ea315b3ef76a8a3da7be99afcf58d2bb (diff)
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: Ming Lei <ming.lei@canonical.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/base/firmware_class.c')
-rw-r--r--drivers/base/firmware_class.c20
1 files changed, 11 insertions, 9 deletions
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 1cbefcfd15f7..1915ad821688 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -243,18 +243,21 @@ static ssize_t firmware_loading_store(struct device *dev,
switch (loading) {
case 1:
/* discarding any previous partial load */
- for (i = 0; i < fw_priv->nr_pages; i++)
- __free_page(fw_priv->pages[i]);
- kfree(fw_priv->pages);
- fw_priv->pages = NULL;
- fw_priv->page_array_size = 0;
- fw_priv->nr_pages = 0;
- set_bit(FW_STATUS_LOADING, &fw_priv->status);
+ 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);
+ fw_priv->pages = NULL;
+ 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);