AZL-48807

In the Linux kernel, the following vulnerability has been resolved:

xhci: Fix Panther point NULL pointer deref at full-speed re-enumeration

re-enumerating full-speed devices after a failed address device command can trigger a NULL pointer dereference.

Full-speed devices may need to reconfigure the endpoint 0 Max Packet Size value during enumeration. Usb core calls usbep0reinit() in this case, which ends up calling xhciconfigureendpoint().

On Panther point xHC the xhciconfigureendpoint() function will additionally check and reserve bandwidth in software. Other hosts do this in hardware

If xHC address device command fails then a new xhcivirtdevice structure is allocated as part of re-enabling the slot, but the bandwidth table pointers are not set up properly here. This triggers the NULL pointer dereference the next time usbep0reinit() is called and xhciconfigureendpoint() tries to check and reserve bandwidth

[46710.713538] usb 3-1: new full-speed USB device number 5 using xhcihcd [46710.713699] usb 3-1: Device not responding to setup address. [46710.917684] usb 3-1: Device not responding to setup address. [46711.125536] usb 3-1: device not accepting address 5, error -71 [46711.125594] BUG: kernel NULL pointer dereference, address: 0000000000000008 [46711.125600] #PF: supervisor read access in kernel mode [46711.125603] #PF: errorcode(0x0000) - not-present page [46711.125606] PGD 0 P4D 0 [46711.125610] Oops: Oops: 0000 [#1] PREEMPT SMP PTI [46711.125615] CPU: 1 PID: 25760 Comm: kworker/1:2 Not tainted 6.10.32 #1 [46711.125620] Hardware name: Gigabyte Technology Co., Ltd. [46711.125623] Workqueue: usbhubwq hubevent [usbcore] [46711.125668] RIP: 0010:xhcireservebandwidth (drivers/usb/host/xhci.c

Fix this by making sure bandwidth table pointers are set up correctly after a failed address device command, and additionally by avoiding checking for bandwidth in cases like this where no actual endpoints are added or removed, i.e. only context for default control endpoint 0 is evaluated.