diff options
author | Ming Lei <ming.lei@canonical.com> | 2013-06-15 16:36:38 +0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-06-18 10:41:55 -0700 |
commit | 875979368eb4cfecff9f0e97625b90cc6009269d (patch) | |
tree | e10845e63381a741f60465d808d9b39f18217c6f /drivers/base/firmware_class.c | |
parent | 7d132055814ef17a6c7b69f342244c410a5e000f (diff) | |
download | linux-875979368eb4cfecff9f0e97625b90cc6009269d.tar.gz linux-875979368eb4cfecff9f0e97625b90cc6009269d.tar.bz2 linux-875979368eb4cfecff9f0e97625b90cc6009269d.zip |
firmware loader: fix use-after-free by double abort
fw_priv->buf is accessed in both request_firmware_load() and
writing to sysfs file of 'loading' context, but not protected
by 'fw_lock' entirely. The patch makes sure that access on
'fw_priv->buf' is protected by the lock.
So fixes the double abort problem reported by nirinA raseliarison:
http://lkml.org/lkml/2013/6/14/188
Reported-and-tested-by: nirinA raseliarison <nirina.raseliarison@gmail.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable <stable@vger.kernel.org> # 3.9
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/base/firmware_class.c')
-rw-r--r-- | drivers/base/firmware_class.c | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c index 4b1f9265887f..01e21037d8fe 100644 --- a/drivers/base/firmware_class.c +++ b/drivers/base/firmware_class.c @@ -450,8 +450,18 @@ static void fw_load_abort(struct firmware_priv *fw_priv) { struct firmware_buf *buf = fw_priv->buf; + /* + * There is a small window in which user can write to 'loading' + * between loading done and disappearance of 'loading' + */ + if (test_bit(FW_STATUS_DONE, &buf->status)) + return; + set_bit(FW_STATUS_ABORT, &buf->status); complete_all(&buf->completion); + + /* avoid user action after loading abort */ + fw_priv->buf = NULL; } #define is_fw_load_aborted(buf) \ @@ -528,7 +538,12 @@ static ssize_t firmware_loading_show(struct device *dev, struct device_attribute *attr, char *buf) { struct firmware_priv *fw_priv = to_firmware_priv(dev); - int loading = test_bit(FW_STATUS_LOADING, &fw_priv->buf->status); + int loading = 0; + + mutex_lock(&fw_lock); + if (fw_priv->buf) + loading = test_bit(FW_STATUS_LOADING, &fw_priv->buf->status); + mutex_unlock(&fw_lock); return sprintf(buf, "%d\n", loading); } @@ -570,12 +585,12 @@ static ssize_t firmware_loading_store(struct device *dev, const char *buf, size_t count) { struct firmware_priv *fw_priv = to_firmware_priv(dev); - struct firmware_buf *fw_buf = fw_priv->buf; + struct firmware_buf *fw_buf; int loading = simple_strtol(buf, NULL, 10); int i; mutex_lock(&fw_lock); - + fw_buf = fw_priv->buf; if (!fw_buf) goto out; @@ -777,10 +792,6 @@ static void firmware_class_timeout_work(struct work_struct *work) struct firmware_priv, timeout_work.work); mutex_lock(&fw_lock); - if (test_bit(FW_STATUS_DONE, &(fw_priv->buf->status))) { - mutex_unlock(&fw_lock); - return; - } fw_load_abort(fw_priv); mutex_unlock(&fw_lock); } @@ -861,8 +872,6 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent, cancel_delayed_work_sync(&fw_priv->timeout_work); - fw_priv->buf = NULL; - device_remove_file(f_dev, &dev_attr_loading); err_del_bin_attr: device_remove_bin_file(f_dev, &firmware_attr_data); |