Re: [PATCH] xhci-ring: Fix Null pointer dereference

[Mathias Nyman]

On 08/28/2014 03:36 PM, Ricardo Ribalda Delgado wrote:
> Hello Mathias
> 
> This is the dmesg output after your patch. No WARN(), no crash :), but
> still some weird messages:
> 
> [  146.511623] usb 2-2: new SuperSpeed USB device number 2 using xhci_hcd
> [  146.531652] usb 2-2: New USB device found, idVendor=0525, idProduct=a4a5
> [  146.531661] usb 2-2: New USB device strings: Mfr=3, Product=4, SerialNumber=0
> [  146.531666] usb 2-2: Product: Mass Storage Gadget
> [  146.531670] usb 2-2: Manufacturer: Linux 3.16.0-qtec-standard+ with net2280
> [  147.772743] usb-storage 2-2:1.0: USB Mass Storage device detected
> [  147.773018] usb-storage 2-2:1.0: Quirks match for vid 0525 pid a4a5: 10000
> [  147.773185] scsi host6: usb-storage 2-2:1.0
> [  147.773361] usbcore: registered new interface driver usb-storage
> [  147.788950] usbcore: registered new interface driver uas
> [  148.772699] scsi 6:0:0:0: Direct-Access     Linux    File-Stor
> Gadget 0316 PQ: 0 ANSI: 2
> [  148.773192] sd 6:0:0:0: Attached scsi generic sg2 type 0
> [  148.774860] sd 6:0:0:0: [sdb] 32768 512-byte logical blocks: (16.7
> MB/16.0 MiB)
> [  148.888294] usb 2-2: reset SuperSpeed USB device number 2 using xhci_hcd
> [  148.905202] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc88
> [  148.905207] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc40
> [  148.906324] xhci_hcd 0000:0e:00.0: Error: Failed finding new dequeue state
> [  148.912639] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
> [  149.014972] sd 6:0:0:0: [sdb] Write cache: enabled, read cache:
> enabled, doesn't support DPO or FUA
> [  149.128640] usb 2-2: reset SuperSpeed USB device number 2 using xhci_hcd
> [  149.145953] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc88
> [  149.145963] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc40
> [  149.147525] xhci_hcd 0000:0e:00.0: Error: Failed finding new dequeue state
> [  149.268626] usb 2-2: reset SuperSpeed USB device number 2 using xhci_hcd
> [  149.285563] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc88
> [  149.285573] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc40
> [  149.286904] xhci_hcd 0000:0e:00.0: Error: Failed finding new dequeue state
> [  149.404621] usb 2-2: reset SuperSpeed USB device number 2 using xhci_hcd
> [  149.421397] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc88
> [  149.421404] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc40
> [  149.422855] xhci_hcd 0000:0e:00.0: Error: Failed finding new dequeue state
> [  149.431667]  sdb: unknown partition table
> [  149.544713] usb 2-2: reset SuperSpeed USB device number 2 using xhci_hcd
> [  149.561649] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc88
> [  149.561658] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc40
> [  149.563021] xhci_hcd 0000:0e:00.0: Error: Failed finding new dequeue state
> [  149.680733] usb 2-2: reset SuperSpeed USB device number 2 using xhci_hcd
> [  149.697766] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc88
> [  149.697774] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc40
> [  149.699025] xhci_hcd 0000:0e:00.0: Error: Failed finding new dequeue state
> [  149.706700] sd 6:0:0:0: [sdb] Write cache: enabled, read cache:
> enabled, doesn't support DPO or FUA
> [  149.706712] sd 6:0:0:0: [sdb] Attached SCSI disk
> [  149.820933] usb 2-2: reset SuperSpeed USB device number 2 using xhci_hcd
> [  149.837887] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc88
> [  149.837895] xhci_hcd 0000:0e:00.0: xHCI xhci_drop_endpoint called
> with disabled ep ffff880036f3cc40
> [  149.839242] xhci_hcd 0000:0e:00.0: Error: Failed finding new dequeue state
> [  155.752101] usb 3-1.5.6: reset high-speed USB device number 10 using ehci-pci
> [  155.866642] cdc_acm 3-1.5.6:1.1: This device cannot do calls on its
> own. It is not a modem.
> [  155.866756] cdc_acm 3-1.5.6:1.1: ttyACM0: USB ACM device
> [  155.867613] usb 3-1.5.6: usbfs: process 1521 (pool) did not claim
> interface 0 before use
> [  160.471327] pool[1680]: segfault at fffffffffc0e61c0 ip
> 00007f570f036200 sp 00007f570639f0d0 error 5 in
> libc-2.19.so[7f570efee000+19f000]
> 
> Thanks!
> 

Thanks, I see you already found bug 75521 
https://bugzilla.kernel.org/show_bug.cgi?id=75521

I think this is the same cause.
Currently I suspect that one halted endpoint is not handled before the entire device is reset.
After device reset we try to handle the old halted endpoint that has a pointer to a invalid old dequeue state.

I'll see If I can make a patch that clears all pending halted endpoint states (xhci software internal states) when a device is reset.

If I send testpatches to the bug can you try them out on top of 3.17-rc2?

-Mathias 
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