net: usb: net1080: validate packet_len before pad-byte access in rx_fixup

In the Linux kernel, the following vulnerability has been resolved: net: usb: net1080: validate packet_len before pad-byte access in rx_fixup For an even packet_len, net1080_rx_fixup() reads the pad byte at skb->data[packet_len] before the skb->len != packet_len check further down, and packet_len is only bounded against NC_MAX_PACKET. A malicious NetChip 1080 device can send a short frame advertising a large even packet_len (e.g. 0x4000), so the pad-byte read lands past the end of the skb: BUG: KASAN: slab-out-of-bounds in net1080_rx_fixup Read of size 1 at addr ffff8880106c83c6 by task ksoftirqd/0/14 ... net1080_rx_fixup (drivers/net/usb/net1080.c:384) usbnet_bh (drivers/net/usb/usbnet.c:1589) process_one_work (kernel/workqueue.c:3322) bh_worker (kernel/workqueue.c:3708) tasklet_action (kernel/softirq.c:965) handle_softirqs (kernel/softirq.c:622) ... Reject the frame when packet_len >= skb->len before reading.