Re: kernel BUG in new r8188eu

[Larry Finger]

On 7/31/21 1:53 PM, Fabio Aiuto wrote:
> Hi all,
>
> On Sat, Jul 31, 2021 at 11:18:10AM -0500, Larry Finger wrote:
> > On 7/31/21 12:37 AM, Greg Kroah-Hartman wrote:
> > > Is this a new regression due to the recent cleanups, or something that
> > > has always been here?
> >
> > I suspect that it has been there forever. I was just doing the kinds of
> > things a user might do, and locked up my box.
> >
> > > As for the error, looks like someone is reading to an address that is
> > > in userspace without doing the proper copy_from_user() thing.  Do you
> > > have a full traceback?
> >
> >   BUG: unable to handle page fault for address: ffffeb020003b848
> >   #PF: supervisor read access in kernel mode
> >   #PF: error_code(0x0000) - not-present page
> >   PGD 0 P4D 0
> >   Oops: 0000 [#1] SMP PTI
> >   CPU: 2 PID: 45 Comm: kworker/2:1 Tainted: G         C O
> > 5.14.0-rc2-00157-g390c661543a8 #8
> >   Hardware name: TOSHIBA TECRA A50-A/TECRA A50-A, BIOS Version 4.50   09/29/2014
> >   Workqueue: usb_hub_wq hub_event [usbcore]
> >   RIP: 0010:kfree+0x68/0x2c0
> >   Code: 01 e5 0f 82 5f 02 00 00 48 b8 00 00 00 80 7f 77 00 00 48 01 c5 48 b8
> > 00 00 00 00 00 ea ff ff 48 c1 ed 0c 48 c1 e5 06 48 01 c5 <48> 8b 45 0>
> >   RSP: 0018:ffffc900001efa78 EFLAGS: 00010282
> >   RAX: ffffea0000000000 RBX: ffffc90000ee1028 RCX: 000000008010000d
> >   RDX: 0000000000000000 RSI: ffffffffa149eddf RDI: ffffc90000ee1578
> >   RBP: ffffeb020003b840 R08: 0000000000000001 R09: 0000000000000001
> >   R10: 0000000000000000 R11: ffff888121c0e400 R12: ffffc90000ee1578
> >   R13: ffff888101fd0000 R14: ffff888101fd0030 R15: 0000000000000003
> >   FS:  0000000000000000(0000) GS:ffff888323280000(0000) knlGS:0000000000000000
> >   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >   CR2: ffffeb020003b848 CR3: 000000000220a002 CR4: 00000000001706e0
> >   Call Trace:
> >    ? kfree+0x25a/0x2c0
> >    rtw_free_mlme_priv_ie_data+0x15/0xf8 [r8188eu]
> >    _rtw_free_mlme_priv+0xe/0x30 [r8188eu]
> >    rtw_free_mlme_priv+0x1a/0x47 [r8188eu]
> >    rtw_free_drv_sw+0x5c/0x1ae [r8188eu]
> >    rtw_usb_if1_deinit+0x67/0xcd [r8188eu]
> >    rtw_dev_remove+0x5a/0xf4 [r8188eu]
> >    usb_unbind_interface+0x8a/0x270 [usbcore]
> >    ? kernfs_find_ns+0x35/0xd0
> >    __device_release_driver+0x1a0/0x260
> >    device_release_driver+0x24/0x30
> >    bus_remove_device+0xd8/0x140
> >    device_del+0x18b/0x3e0
> >    ? kobject_cleanup+0x49/0x130
> >    usb_disable_device+0xd9/0x260 [usbcore]
> >    usb_disconnect.cold+0x7b/0x201 [usbcore]
> >    hub_port_connect+0x88/0x8d0 [usbcore]
> >    ? kfree+0xe6/0x2c0
> >    hub_port_connect_change+0xb1/0x3a0 [usbcore]
> >    port_event+0x5d4/0x720 [usbcore]
> >    hub_event+0x1db/0x430 [usbcore]
> >    process_one_work+0x1dd/0x3a0
> >    worker_thread+0x50/0x3f0
> >    ? rescuer_thread+0x390/0x390
> >    kthread+0x128/0x140
> >    ? set_kthread_struct+0x40/0x40
> >    ret_from_fork+0x22/0x30
> >   Modules linked in: snd_seq_dummy snd_hrtimer snd_seq snd_seq_device ctr ccm
> > r8188eu(C) rfcomm rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs>
> >    crypto_simd cryptd i915 i2c_algo_bit serio_raw ttm drm_kms_helper
> > syscopyarea sysfillrect sysimgblt fb_sys_fops drm xhci_pci ehci_pci xhci_hcd
> > >
> >   CR2: ffffeb020003b848
> >   ---[ end trace f5f4e2b2680b5fd7 ]---
> >
> > The driver is allocating some buffers using kmalloc variants, and others
> > using vmalloc. I checked to see if there was confusion on which form of free
> > should be used, but this one is allocated with kmalloc and freed with kfree,
> > which should be OK.
> >
> > Larry
>
> Maybe hostapd is involved. Try killing hostapd before and then
> unplug the dongle... does the system freeze?
>
> #include "../include/rtw_android.h"
> int rtw_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
> {
>          struct iwreq *wrq = (struct iwreq *)rq;
>          int ret = 0;
>
>          switch (cmd) {
>          case RTL_IOCTL_WPA_SUPPLICANT:
>                  ret = wpa_supplicant_ioctl(dev, &wrq->u.data);
>                  break;
> #ifdef CONFIG_88EU_AP_MODE
>          case RTL_IOCTL_HOSTAPD:
>                  ret = rtw_hostapd_ioctl(dev, &wrq->u.data);
>          	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> I think that someone tries to write the wrong fields while
> freeing memory...
>
> 	break;
> #endif /*  CONFIG_88EU_AP_MODE */
>          case SIOCDEVPRIVATE:
>
> static int rtw_hostapd_ioctl(struct net_device *dev, struct iw_point *p)
> {
>          struct ieee_param *param;
>          int ret = 0;
>          struct adapter *padapter = (struct adapter *)rtw_netdev_priv(dev);
>
> ...
>
>          switch (param->cmd) {
>          case RTL871X_HOSTAPD_FLUSH:
>                  ret = rtw_hostapd_sta_flush(dev);
>                  break;
> ...
>          case RTL871X_HOSTAPD_SET_WPS_BEACON:
>                  ret = rtw_set_wps_beacon(dev, param, p->length);
>                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 		break;
>
> static int rtw_set_wps_beacon(struct net_device *dev, struct ieee_param *param, int len)
> {
>          int ret = 0;
>         
> ...
>
>                  memcpy(pmlmepriv->wps_beacon_ie, param->u.bcn_ie.buf, ie_len);
> 		^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 		maybe hotsapd does some ioctl at the wrong moment.
>
> Just to verify, we could kill hostapd, if ever runs in your machine...

No, hostapd was not involved. I was using r8188eu in STA mode.

Larry