Re: tty_register_device NULL pointer dereference in 2.6.31-rc4

Oliver Hartkopp
2009-08-01T09:15:24Z

Dave Young wrote:
> On Fri, Jul 31, 2009 at 01:20:19PM +0200, Oliver Hartkopp wrote:

>> applied this patch and replaced mdelay(100) with msleep(100).
>>
>> I got two crashes and three proper boots.
>>
>> The crashes look like the formerly posted screenshots.
>> When it boots properly i can see the delay in the boot process.
>>
>> Does this help?
>
> Yes, I think so.
>
> Please unapply the before two patch, try the following v2 patch instead.
> Changes from v1: fixes 'goto' path again, make tty init before sock init.

Hi Dave,

i did a 'git reset --hard' to get back to vanilla 2.6.31-rc4 .

Applied the v2 patch and booted five times without any problems.

I'll keep you informed if anything changes ;-)

Thanks,
Oliver

> ---
>
> rfcomm tty may be used before rfcomm_tty_driver initilized,
> The problem is that now socket layer init before tty layer, if userspace
> program do socket callback right here then oops will happen.
>
> reporting in:
> http://marc.info/?l=linux-bluetooth&m=124404919324542&w=2
>
> make 3 changes:
> 1. remove #ifdef in rfcomm/core.c,
> make it blank function when rfcomm tty not selected in rfcomm.h
>
> 2. tune the rfcomm_init error patch to ensure
> tty driver initilized before rfcomm socket usage.
>
> 3. remove __exit for rfcomm_cleanup_sockets
> because above change need call it in a __init function.
>
>
> CC: Alan Cox <alan@lxorguk.ukuu.org.uk>
> Reported-by: Oliver Hartkopp <oliver@hartkopp.net>
> Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
> --
> include/net/bluetooth/rfcomm.h | 13 ++++++++++++-
> net/bluetooth/rfcomm/core.c | 29 ++++++++++++++++++++---------
> net/bluetooth/rfcomm/sock.c | 2 +-
> 3 files changed, 33 insertions(+), 11 deletions(-)
>
> --- linux-2.6.orig/include/net/bluetooth/rfcomm.h 2009-08-01 10:53:18.000000000 +0800
> +++ linux-2.6/include/net/bluetooth/rfcomm.h 2009-08-01 10:55:29.000000000 +0800
> @@ -355,7 +355,18 @@ struct rfcomm_dev_list_req {
> };
>
> int rfcomm_dev_ioctl(struct sock *sk, unsigned int cmd, void __user *arg);
> +
> +#ifdef CONFIG_BT_RFCOMM_TTY
> int rfcomm_init_ttys(void);
> void rfcomm_cleanup_ttys(void);
> -
> +#else
> +static inline int rfcomm_init_ttys(void)
> +{
> + return 0;
> +}
> +static inline int rfcomm_cleanup_ttys(void)
> +{
> + return 0;
> +}
> +#endif
> #endif /* __RFCOMM_H */
> --- linux-2.6.orig/net/bluetooth/rfcomm/core.c 2009-08-01 10:53:18.000000000 +0800
> +++ linux-2.6/net/bluetooth/rfcomm/core.c 2009-08-01 11:03:24.000000000 +0800
> @@ -2080,28 +2080,41 @@ static CLASS_ATTR(rfcomm_dlc, S_IRUGO, r
> /* ---- Initialization ---- */
> static int __init rfcomm_init(void)
> {
> + int ret;
> +
> l2cap_load();
>
> hci_register_cb(&rfcomm_cb);
>
> rfcomm_thread = kthread_run(rfcomm_run, NULL, "krfcommd");
> if (IS_ERR(rfcomm_thread)) {
> - hci_unregister_cb(&rfcomm_cb);
> - return PTR_ERR(rfcomm_thread);
> + ret = PTR_ERR(rfcomm_thread);
> + goto out_thread;
> }
>
> if (class_create_file(bt_class, &class_attr_rfcomm_dlc) < 0)
> BT_ERR("Failed to create RFCOMM info file");
>
> - rfcomm_init_sockets();
> -
> -#ifdef CONFIG_BT_RFCOMM_TTY
> - rfcomm_init_ttys();
> -#endif
> + ret = rfcomm_init_ttys();
> + if (ret)
> + goto out_tty;
> +
> + ret = rfcomm_init_sockets();
> + if (ret)
> + goto out_sock;
>
> BT_INFO("RFCOMM ver %s", VERSION);
>
> return 0;
> +
> +out_sock:
> + rfcomm_cleanup_ttys();
> +out_tty:
> + kthread_stop(rfcomm_thread);
> +out_thread:
> + hci_unregister_cb(&rfcomm_cb);
> +
> + return ret;
> }
>
> static void __exit rfcomm_exit(void)
> @@ -2112,9 +2125,7 @@ static void __exit rfcomm_exit(void)
>
> kthread_stop(rfcomm_thread);
>
> -#ifdef CONFIG_BT_RFCOMM_TTY
> rfcomm_cleanup_ttys();
> -#endif
>
> rfcomm_cleanup_sockets();
> }
> --- linux-2.6.orig/net/bluetooth/rfcomm/sock.c 2009-08-01 10:53:18.000000000 +0800
> +++ linux-2.6/net/bluetooth/rfcomm/sock.c 2009-08-01 10:55:29.000000000 +0800
> @@ -1132,7 +1132,7 @@ error:
> return err;
> }
>
> -void __exit rfcomm_cleanup_sockets(void)
> +void rfcomm_cleanup_sockets(void)
> {
> class_remove_file(bt_class, &class_attr_rfcomm);
>