This is a note to let you know that I've just added the patch titled
firmware loader: fix use-after-free by double abort
to the 3.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
firmware-loader-fix-use-after-free-by-double-abort.patch
and it can be found in the queue-3.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 875979368eb4cfecff9f0e97625b90cc6009269d Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@xxxxxxxxxxxxx>
Date: Sat, 15 Jun 2013 16:36:38 +0800
Subject: firmware loader: fix use-after-free by double abort
From: Ming Lei <ming.lei@xxxxxxxxxxxxx>
commit 875979368eb4cfecff9f0e97625b90cc6009269d upstream.
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@xxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/base/firmware_class.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -450,8 +450,18 @@ static void fw_load_abort(struct firmwar
{
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(str
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(st
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 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
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);
Patches currently in stable-queue which might be from ming.lei@xxxxxxxxxxxxx are
queue-3.9/firmware-loader-fix-use-after-free-by-double-abort.patch
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