CVE-2025-21877 — usbnet: gl620a: fix endpoint checking in genelink_bind()

Affected: Linux

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

usbnet: gl620a: fix endpoint checking in genelink_bind()

Syzbot reports [1] a warning in usb_submit_urb() triggered by inconsistencies between expected and actually present endpoints in gl620a driver. Since genelink_bind() does not properly verify whether specified eps are in fact provided by the device, in this case, an artificially manufactured one, one may get a mismatch.

Fix the issue by resorting to a usbnet utility function usbnet_get_endpoints(), usually reserved for this very problem. Check for endpoints and return early before proceeding further if any are missing.

[1] Syzbot report: usb 5-1: Manufacturer: syz usb 5-1: SerialNumber: syz usb 5-1: config 0 descriptor?? gl620a 5-1:0.23 usb0: register 'gl620a' at usb-dummy_hcd.0-1, ... ------------[ cut here ]------------ usb 5-1: BOGUS urb xfer, pipe 3 != type 1 WARNING: CPU: 2 PID: 1841 at drivers/usb/core/urb.c:503 usb_submit_urb+0xe4b/0x1730 drivers/usb/core/urb.c:503 Modules linked in: CPU: 2 UID: 0 PID: 1841 Comm: kworker/2:2 Not tainted 6.12.0-syzkaller-07834-g06afb0f36106 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: mld mld_ifc_work RIP: 0010:usb_submit_urb+0xe4b/0x1730 drivers/usb/core/urb.c:503 ... Call Trace: <TASK> usbnet_start_xmit+0x6be/0x2780 drivers/net/usb/usbnet.c:1467 __netdev_start_xmit include/linux/netdevice.h:5002 [inline] netdev_start_xmit include/linux/n…

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CVE-2025-21877 — usbnet: gl620a: fix endpoint checking in genelink_bind()