Re: kernel BUG in new r8188eu

Larry Finger
2021-07-31T16:18:39Z

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