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

Bluetooth: hci_qca: fix NULL pointer dereference in qca_setup() for non-serdev device

hu->serdev is NULL for hci_uart attached via non-serdev paths, but
qca_setup() unconditionally calls serdev_device_get_drvdata(hu->serdev)
and dereferences the result, causing a NULL pointer dereference.

Fix by guarding the dereference with a NULL check, consistent with the
rest of qca_setup().