linux-kernel - [ 006/117] firmware loader: fix pending_fw

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20130925001741.558238953@linuxfoundation.org>
Date:	Tue, 24 Sep 2013 17:17:52 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Maxime Bizon <mbizon@...ebox.fr>,
	Ming Lei <ming.lei@...onical.com>
Subject: [ 006/117] firmware loader: fix pending_fw_head list corruption

3.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Maxime Bizon <mbizon@...ebox.fr>

commit 1eeeef153c02f5856ec109fa532eb5f31c39f85c upstream.

Got the following oops just before reboot:

Unable to handle kernel NULL pointer dereference at virtual address 00000000
[<8028d300>] (__list_del_entry+0x44/0xac)
[<802e3320>] (__fw_load_abort.part.13+0x1c/0x50)
[<802e337c>] (fw_shutdown_notify+0x28/0x50)
[<80034f80>] (notifier_call_chain.isra.1+0x5c/0x9c)
[<800350ec>] (__blocking_notifier_call_chain+0x44/0x58)
[<80035114>] (blocking_notifier_call_chain+0x14/0x18)
[<80035d64>] (kernel_restart_prepare+0x14/0x38)
[<80035d94>] (kernel_restart+0xc/0x50)

The following race condition triggers here:

  _request_firmware_load()
  device_create_file(...)
  kobject_uevent(...)
  (schedule)
                                       (resume)
                                       firmware_loading_store(1)
                                       firmware_loading_store(0)
                                       list_del_init(&buf->pending_list)
                                       (schedule)
  (resume)
  list_add(&buf->pending_list, &pending_fw_head);
  wait_for_completion(&buf->completion);

causing an oops later when walking pending_list after the firmware has
been released.

The proposed fix is to move the list_add() before sysfs attribute
creation.

Signed-off-by: Maxime Bizon <mbizon@...ebox.fr>
Acked-by: Ming Lei <ming.lei@...onical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/base/firmware_class.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -868,8 +868,15 @@ static int _request_firmware_load(struct
 		goto err_del_dev;
 	}
 
+	mutex_lock(&fw_lock);
+	list_add(&buf->pending_list, &pending_fw_head);
+	mutex_unlock(&fw_lock);
+
 	retval = device_create_file(f_dev, &dev_attr_loading);
 	if (retval) {
+		mutex_lock(&fw_lock);
+		list_del_init(&buf->pending_list);
+		mutex_unlock(&fw_lock);
 		dev_err(f_dev, "%s: device_create_file failed\n", __func__);
 		goto err_del_bin_attr;
 	}
@@ -884,10 +891,6 @@ static int _request_firmware_load(struct
 		kobject_uevent(&fw_priv->dev.kobj, KOBJ_ADD);
 	}
 
-	mutex_lock(&fw_lock);
-	list_add(&buf->pending_list, &pending_fw_head);
-	mutex_unlock(&fw_lock);
-
 	wait_for_completion(&buf->completion);
 
 	cancel_delayed_work_sync(&fw_priv->timeout_work);


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/