On Wed, Jul 22, 2020 at 07:57:48PM +0800, WeitaoWangoc wrote: > This bug is found in Zhaoxin platform, but it's a commom code bug. > Fail sequence: > step1: Unbind UHCI controller from native driver; > step2: Bind UHCI controller to vfio-pci, which will put UHCI controller in one vfio > group's device list and set UHCI's dev->driver_data to struct vfio-pci(for UHCI) Hah, that works? How do you do that properly? What code does that? > step3: Unbind EHCI controller from native driver, will try to tell UHCI native driver > that "I'm removed by set companion_hcd->self.hs_companion to NULL. However, > companion_hcd get from UHCI's dev->driver_data that has modified by vfio-pci > already.So, the vfio-pci structure will be damaged! Because you are messing around with bind/unbind "by hand", which is never guaranteed to work properly. It's amazing any of that works at all... > step4: Bind EHCI controller to vfio-pci driver, which will put EHCI controller in the > same vfio group as UHCI controller; > ... ... > step5: Unbind UHCI controller from vfio-pci, which will delete UHCI from vfio group' > device list that has been damaged in step 3. So,delete operation can random > result into a NULL pointer dereference with the below stack dump. > step6: Bind UHCI controller to native driver; > step7: Unbind EHCI controller from vfio-pci, which will try to remove EHCI controller > from the vfio group; > step8: Bind EHCI controller to native driver; > > [ 929.114641] uhci_hcd 0000:00:10.0: remove, state 1 > [ 929.114652] usb usb1: USB disconnect, device number 1 > [ 929.114655] usb 1-1: USB disconnect, device number 2 > [ 929.270313] usb 1-2: USB disconnect, device number 3 > [ 929.318404] uhci_hcd 0000:00:10.0: USB bus 1 deregistered > [ 929.343029] uhci_hcd 0000:00:10.1: remove, state 4 > [ 929.343045] usb usb3: USB disconnect, device number 1 > [ 929.343685] uhci_hcd 0000:00:10.1: USB bus 3 deregistered > [ 929.369087] ehci-pci 0000:00:10.7: remove, state 4 > [ 929.369102] usb usb4: USB disconnect, device number 1 > [ 929.370325] ehci-pci 0000:00:10.7: USB bus 4 deregistered > [ 932.398494] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 > [ 932.398496] PGD 42a67d067 P4D 42a67d067 PUD 42a65f067 PMD 0 > [ 932.398502] Oops: 0002 [#2] SMP NOPTI > [ 932.398505] CPU: 2 PID: 7824 Comm: vfio_unbind.sh Tainted: P D 4.19.65-2020051917-rainos #1 4.19 is a bit old, what about 5.7? > [ 932.398506] Hardware name: Shanghai Zhaoxin Semiconductor Co., Ltd. HX002EH/HX002EH, > BIOS HX002EH0_01_R480_R_200408 04/08/2020 > [ 932.398513] RIP: 0010:vfio_device_put+0x31/0xa0 [vfio] > [ 932.398515] Code: 89 e5 41 54 53 4c 8b 67 18 48 89 fb 49 8d 74 24 30 e8 e3 0e f3 de > 84 c0 74 67 48 8b 53 20 48 8b 43 28 48 8b 7b 18 48 89 42 08 <48> 89 10 > 48 b8 00 01 00 00 00 00 ad de 48 89 43 20 48 b8 00 02 00 > [ 932.398516] RSP: 0018:ffffbbfd04cffc18 EFLAGS: 00010202 > [ 932.398518] RAX: 0000000000000000 RBX: ffff92c7ea717880 RCX: 0000000000000000 > [ 932.398519] RDX: ffff92c7ea713620 RSI: ffff92c7ea713630 RDI: ffff92c7ea713600 > [ 932.398521] RBP: ffffbbfd04cffc28 R08: ffff92c7f02a8080 R09: ffff92c7efc03980 > [ 932.398522] R10: ffffbbfd04cff9a8 R11: 0000000000000000 R12: ffff92c7ea713600 > [ 932.398523] R13: ffff92c7ed8bb0a8 R14: ffff92c7ea717880 R15: 0000000000000000 > [ 932.398525] FS: 00007f3031500740(0000) GS:ffff92c7f0280000(0000) knlGS:0000000000000000 > [ 932.398526] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 932.398527] CR2: 0000000000000000 CR3: 0000000428626004 CR4: 0000000000160ee0 > [ 932.398528] Call Trace: > [ 932.398534] vfio_del_group_dev+0xe8/0x2a0 [vfio] > [ 932.398539] ? __blocking_notifier_call_chain+0x52/0x60 > [ 932.398542] ? do_wait_intr_irq+0x90/0x90 > [ 932.398546] ? iommu_bus_notifier+0x75/0x100 > [ 932.398551] vfio_pci_remove+0x20/0xa0 [vfio_pci] > [ 932.398554] pci_device_remove+0x3e/0xc0 > [ 932.398557] device_release_driver_internal+0x17a/0x240 > [ 932.398560] device_release_driver+0x12/0x20 > [ 932.398561] unbind_store+0xee/0x180 > [ 932.398564] drv_attr_store+0x27/0x40 > [ 932.398567] sysfs_kf_write+0x3c/0x50 > [ 932.398568] kernfs_fop_write+0x125/0x1a0 > [ 932.398572] __vfs_write+0x3a/0x190 > [ 932.398575] ? apparmor_file_permission+0x1a/0x20 > [ 932.398577] ? security_file_permission+0x3b/0xc0 > [ 932.398581] ? _cond_resched+0x1a/0x50 > [ 932.398582] vfs_write+0xb8/0x1b0 > [ 932.398584] ksys_write+0x5c/0xe0 > [ 932.398586] __x64_sys_write+0x1a/0x20 > [ 932.398589] do_syscall_64+0x5a/0x110 > [ 932.398592] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Using virt-manager/qemu to boot guest os, we can see the same fail sequence! > > Fix this by check for UHCI driver loaded or not before modifiy UHCI's dev->driver_data, > which will happen in ehci native driver probe/remove. > > Signed-off-by: WeitaoWangoc <WeitaoWang-oc@xxxxxxxxxxx> > --- > drivers/usb/core/hcd-pci.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/usb/core/hcd-pci.c b/drivers/usb/core/hcd-pci.c > index 1547aa6..484f2a0 100644 > --- a/drivers/usb/core/hcd-pci.c > +++ b/drivers/usb/core/hcd-pci.c > @@ -34,6 +34,7 @@ static DECLARE_RWSEM(companions_rwsem); > #define CL_OHCI PCI_CLASS_SERIAL_USB_OHCI > #define CL_EHCI PCI_CLASS_SERIAL_USB_EHCI > > +#define PCI_DEV_DRV_FLAG 2 Why is the USB core allowed to touch a private PCI structure field? I do not think this is allowed. And why is this a USB host controller-specific issue, shouldn't this type of thing be fixed in the PCI core? thanks, greg k-h
