CVE-2026-64540

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

usbnet: gl620a: fix out-of-bounds read in genelinkrxfixup()

genelinkrxfixup() splits an aggregated RX frame into its individual packets, using a per-packet length taken from device-supplied data. That length is only bounded by GLMAXPACKET_LEN (1514); it is never compared against how many bytes were actually received.

A malicious GeneLink (GL620A) device can therefore send a short URB whose header claims packet_count > 1 and a first packet of up to 1514 bytes.

skb_put_data(gl_skb, packet->packet_data, size);

then copies past the end of the receive buffer and hands the adjacent slab contents up the network stack, an out-of-bounds read that leaks kernel heap. No privilege is required: the path runs in the usbnet RX softirq as soon as the interface is up.

BUG: KASAN: slab-out-of-bounds in genelinkrxfixup (drivers/net/usb/gl620a.c:112) Read of size 1514 at addr ffff888011309708 by task ksoftirqd/0/14 Call Trace: ... __asanmemcpy (mm/kasan/shadow.c:105) genelinkrxfixup (include/linux/skbuff.h:2814 drivers/net/usb/gl620a.c:112) usbnetbh (drivers/net/usb/usbnet.c:572 drivers/net/usb/usbnet.c:1589) processonework (kernel/workqueue.c:3322) bhworker (kernel/workqueue.c:3405) taskletaction (kernel/softirq.c:965) handlesoftirqs (kernel/softirq.c:622) runksoftirqd (kernel/softirq.c:1076) ...

skb_pull() already verifies that the requested length fits the buffer and returns NULL otherwise. Move it ahead of the copy and check its result, so a packet that overruns the received data is rejected before it is read. Well-formed frames, whose packets are fully present, are unaffected.