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@freebox.fr>
Acked-by: Ming Lei <ming.lei@canonical.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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;
}
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);