CVE-2026-98756: usb: cdns3: Fix NULL pointer dereference in cdns3_pci_probe

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

usb: cdns3: Fix NULL pointer dereference in cdns3pciprobe

The Cadence USBSS controller is a two-function PCI device. The first probed function allocates the driver data and stores it with pcisetdrvdata(), while the second function reuses it via pcigetdrvdata() when pciisenabled() reports that the first function has already been probed.

When the second function is probed while the first one has been enabled but has not yet set its driver data, pcigetdrvdata() returns NULL, and the subsequent wrap->devfn assignment dereferences a NULL pointer and crashes the kernel. logs: Call trace: cdns3pciprobe+0xa4/0x300 localpciprobe+0x44/0xa8 pcicallprobe+0x54/0x158 pcideviceprobe+0x84/0x100 reallyprobe+0x184/0x3d0 driverprobedevice+0x80/0x178 driverprobedevice+0x44/0xe8 driverattach+0xec/0x1f8 busforeachdev+0x7c/0xe0 driverattach+0x28/0x38 busadddriver+0x110/0x238 driverregister+0x64/0x128 pciregisterdriver+0x50/0x60 cdns3pcidriverinit+0x28/0x38 dooneinitcall+0x5c/0x280 doinitcalls+0x104/0x1d8 kernelinitfreeable+0x140/0x218 kernelinit+0x28/0x1f8 retfromfork+0x10/0x20

Return -EPROBEDEFER in this case so that probing is retried after the first function has completed its probe.