| Message ID | BYAPR11MB2632EDC88523D674D9C63E73FFD10@BYAPR11MB2632.namprd11.prod.outlook.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | 回复: KASAN: use-after-free Read in service_outstanding_interrupt | expand |
Am Dienstag, den 05.01.2021, 04:50 +0000 schrieb Zhang, Qiang: > > ________________________________________ > 发件人: Oliver Neukum <oneukum@suse.com> > 发送时间: 2021年1月5日 0:28 > 收件人: syzbot; andreyknvl@google.com; gregkh@linuxfoundation.org; gustavoars@kernel.org; ingrassia@epigenesys.com; lee.jones@linaro.org; linux-kernel@vger.kernel.org; linux-usb@vger.kernel.org; penguin-kernel@I-love.SAKURA.ne.jp; syzkaller-bugs@googlegroups.com > 主题: Re: KASAN: use-after-free Read in service_outstanding_interrupt > > Am Donnerstag, den 17.12.2020, 19:21 -0800 schrieb syzbot: > > syzbot has found a reproducer for the following issue on: > > > > HEAD commit: 5e60366d Merge tag 'fallthrough-fixes-clang-5.11-rc1' of g.. > > git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing > > console output: https://syzkaller.appspot.com/x/log.txt?x=12c5b623500000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=5cea7506b7139727 > > dashboard link: https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf > > compiler: gcc (GCC) 10.1.0-syz 20200507 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=175adf07500000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1672680f500000 > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: >syzbot+9e04e2df4a32fb661daf@syzkaller.appspotmail.com > > > > #syz test: https://github.com/google/kasan.git 5e60366d > > > > Hello Oliver > > this use-after-free still exists，It can be seen from calltrace that it is > usb_device's object has been released when disconnect, > can add a reference count to usb_device's object to avoid this problem Hi, thanks for your analysis. I think you are correct in your analysis, but I am afraid your fix is not correct. The driver is submitting an URB to a disconnected device. Your fix would prevent a crash, which is definitely good, but we still cannot do that, because the device may be owned by another driver or usbfs at that time. Regards Oliver
--- a/drivers/usb/class/cdc-wdm.c +++ b/drivers/usb/class/cdc-wdm.c @@ -106,6 +106,7 @@ struct wdm_device { struct list_head device_list; int (*manage_power)(struct usb_interface *, int); + struct usb_device *usb_dev; }; static struct usb_driver wdm_driver; @@ -338,6 +339,7 @@ static void free_urbs(struct wdm_device *desc) static void cleanup(struct wdm_device *desc) { + usb_put_dev(desc->usb_dev); kfree(desc->sbuf); kfree(desc->inbuf); kfree(desc->orq); @@ -855,6 +857,7 @@ static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descripto r desc->intf = intf; INIT_WORK(&desc->rxwork, wdm_rxwork); INIT_WORK(&desc->service_outs_intr, service_interrupt_work); + desc->usb_dev = usb_get_dev(interface_to_usbdev(intf)); rv = -EINVAL;