aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorMing Lei <ming.lei@canonical.com>2013-06-15 16:36:38 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-06-18 10:41:55 -0700
commit875979368eb4cfecff9f0e97625b90cc6009269d (patch)
treee10845e63381a741f60465d808d9b39f18217c6f
parent7d132055814ef17a6c7b69f342244c410a5e000f (diff)
downloadvexpress-lsk-875979368eb4cfecff9f0e97625b90cc6009269d.tar.gz
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>
-rw-r--r--drivers/base/firmware_class.c27
1 files changed, 18 insertions, 9 deletions
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 4b1f9265887..01e21037d8f 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);