CVE-2025-21877

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

usbnet: gl620a: fix endpoint checking in genelink_bind()

Syzbot reports [1] a warning in usbsubmiturb() 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 usbnetgetendpoints(), 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-dummyhcd.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 usbsubmiturb+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 mldifcwork RIP: 0010:usbsubmiturb+0xe4b/0x1730 drivers/usb/core/urb.c:503 ... Call Trace: <TASK> usbnetstart_xmit+0x6be/0x2780 drivers/net/usb/usbnet.c:1467 __netdevstartxmit include/linux/netdevice.h:5002 [inline] netdevstartxmit include/linux/netdevice.h:5011 [inline] xmitone net/core/dev.c:3590 [inline] devhardstartxmit+0x9a/0x7b0 net/core/dev.c:3606 schdirectxmit+0x1ae/0xc30 net/sched/sch_generic.c:343 __devxmitskb net/core/dev.c:3827 [inline] __devqueuexmit+0x13d4/0x43e0 net/core/dev.c:4400 devqueuexmit include/linux/netdevice.h:3168 [inline] neighresolveoutput net/core/neighbour.c:1514 [inline] neighresolveoutput+0x5bc/0x950 net/core/neighbour.c:1494 neighoutput include/net/neighbour.h:539 [inline] ip6finishoutput2+0xb1b/0x2070 net/ipv6/ip6output.c:141 _ip6finishoutput net/ipv6/ip6output.c:215 [inline] ip6finishoutput+0x3f9/0x1360 net/ipv6/ip6output.c:226 NFHOOKCOND include/linux/netfilter.h:303 [inline] ip6output+0x1f8/0x540 net/ipv6/ip6output.c:247 dstoutput include/net/dst.h:450 [inline] NFHOOK include/linux/netfilter.h:314 [inline] NFHOOK include/linux/netfilter.h:308 [inline] mldsendpack+0x9f0/0x11d0 net/ipv6/mcast.c:1819 mldsendcr net/ipv6/mcast.c:2120 [inline] mldifcwork+0x740/0xca0 net/ipv6/mcast.c:2651 processonework+0x9c5/0x1ba0 kernel/workqueue.c:3229 processscheduledworks kernel/workqueue.c:3310 [inline] workerthread+0x6c8/0xf00 kernel/workqueue.c:3391 kthread+0x2c1/0x3a0 kernel/kthread.c:389 retfromfork+0x45/0x80 arch/x86/kernel/process.c:147 retfromforkasm+0x1a/0x30 arch/x86/entry/entry64.S:244 </TASK>