Re: [PATCH] XHCI NULL Pointer check in xhci_check_bw_table

[Markus Rechberger <linuxusb.ml@sundtek.de>]

On Mon, 2024-11-18 at 11:36 +0200, Mathias Nyman wrote:
> Hi
> 
> On 17.11.2024 17.32, Sundtek wrote:
> > This patch fixes a NULL Pointer exception when a device using the
> > XHCI
> > controller driver is not properly initialized. It's relatively easy
> > to
> > reproduce with a faulty connection to a USB Harddisk / USB Ethernet
> > adapter.
> > The way I used for testing this patch was to short USB D+/D- and
> > pull
> > them to ground.
> > 
> > We manufacture our own USB devices and use Linux for testing,
> > lately we
> > upgraded the system to Ubuntu noble with Kernel 6.8.0 and our
> > system
> > also crashed multiple times just when plugging in some devices (no
> > commands need to be executed).
> > We connect/disconnect devices > 100 times (eg uploading firmware,
> > do
> > electrical tests etc).
> > 
> > I would rate this issue as highly critical.
> > The problem is triggered via some fallback code in hub.c, a second
> > patch will follow which
> > removes the endpoint reset in the particular fallback.
> > 
> 
> 
> > 2024-11-16T22:14:12.122224+08:00 sundtek-UX32VD kernel: RIP:
> > 0010:xhci_check_bw_table+0x100/0x4d0
> 
> This looks very similar to a null pointer issue I fixed recently.
> Patch should be in 6.11 and recent stable releases:
> 
> af8e119f52e9 xhci: Fix Panther point NULL pointer deref at full-speed
> re-enumeration
> 
> What kernel are you running?


thanks for pointing out to that, I was testing this on Linux 6.8.12.
I will recompile the latest kernel and double check.

your one:
[46711.125623] Workqueue: usb_hub_wq hub_event [usbcore]
[46711.125668] RIP: 0010:xhci_reserve_bandwidth
(drivers/usb/host/xhci.c

vs my one:
kernel: Workqueue: usb_hub_wq hub_event
kernel: RIP: 0010:xhci_check_bw_table+0x100/0x4d0

https://sundtek.de/support/uxvd32.txt

Best Regards,
Markus

> 
> Thanks
> Mathias