CVE-2026-43479
Description
In the Linux kernel, the following vulnerability has been resolved:
net: usb: lan78xx: fix WARN in __netif_napi_del_locked on disconnect
Remove redundant netif_napi_del() call from disconnect path.
A WARN may be triggered in __netif_napi_del_locked() during USB device disconnect:
WARNING: CPU: 0 PID: 11 at net/core/dev.c:7417 __netif_napi_del_locked+0x2b4/0x350
This happens because netif_napi_del() is called in the disconnect path while NAPI is still enabled. However, it is not necessary to call netif_napi_del() explicitly, since unregister_netdev() will handle NAPI teardown automatically and safely. Removing the redundant call avoids triggering the warning.
Full trace: lan78xx 1-1:1.0 enu1: Failed to read register index 0x000000c4. ret = -ENODEV lan78xx 1-1:1.0 enu1: Failed to set MAC down with error -ENODEV lan78xx 1-1:1.0 enu1: Link is Down lan78xx 1-1:1.0 enu1: Failed to read register index 0x00000120. ret = -ENODEV ------------[ cut here ]------------ WARNING: CPU: 0 PID: 11 at net/core/dev.c:7417 __netif_napi_del_locked+0x2b4/0x350 Modules linked in: flexcan can_dev fuse CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 6.16.0-rc2-00624-ge926949dab03 #9 PREEMPT Hardware name: SKOV IMX8MP CPU revC - bd500 (DT) Workqueue: usb_hub_wq hub_event pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : __netif_napi_del_locked+0x2b4/0x350 lr : __netif_napi_del_locked+0x7c/0x350 sp : ffffffc085b673c0 x29: ffffffc085b673c0 x28: ffffff800b7f2000 x27: ffffff800b7f20d8 x26: ffffff80110bcf58 x25: ffffff80110bd978 x24: 1ffffff0022179eb x23: ffffff80110bc000 x22: ffffff800b7f5000 x21: ffffff80110bc000 x20: ffffff80110bcf38 x19: ffffff80110bcf28 x18: dfffffc000000000 x17: ffffffc081578940 x16: ffffffc08284cee0 x15: 0000000000000028 x14: 0000000000000006 x13: 0000000000040000 x12: ffffffb0022179e8 x11: 1ffffff0022179e7 x10: ffffffb0022179e7 x9 : dfffffc000000000 x8 : 0000004ffdde8619 x7 : ffffff80110bcf3f x6 : 0000000000000001 x5 : ffffff80110bcf38 x4 : ffffff80110bcf38 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 1ffffff0022179e7 x0 : 0000000000000000 Call trace: __netif_napi_del_locked+0x2b4/0x350 (P) lan78xx_disconnect+0xf4/0x360 usb_unbind_interface+0x158/0x718 device_remove+0x100/0x150 device_release_driver_internal+0x308/0x478 device_release_driver+0x1c/0x30 bus_remove_device+0x1a8/0x368 device_del+0x2e0/0x7b0 usb_disable_device+0x244/0x540 usb_disconnect+0x220/0x758 hub_event+0x105c/0x35e0 process_one_work+0x760/0x17b0 worker_thread+0x768/0xce8 kthread+0x3bc/0x690 ret_from_fork+0x10/0x20 irq event stamp: 211604 hardirqs last enabled at (211603): [] _raw_spin_unlock_irqrestore+0x84/0x98 hardirqs last disabled at (211604): [] el1_dbg+0x24/0x80 softirqs last enabled at (211296): [] handle_softirqs+0x820/0xbc8 softirqs last disabled at (210993): [] __do_softirq+0x18/0x20 ---[ end trace 0000000000000000 ]--- lan78xx 1-1:1.0 enu1: failed to kill vid 0081/0
Patches
3395a8b903738312c816c6bc320ce2bd1c184Vulnerability mechanics
Root cause
"Redundant netif_napi_del() call in the disconnect path while NAPI is still enabled triggers a WARN in __netif_napi_del_locked()."
Attack vector
An attacker with physical USB access can trigger the vulnerability by disconnecting a lan78xx-based USB Ethernet device while it is active. The disconnect causes register read failures (e.g., -ENODEV), which leads to the driver's disconnect path calling netif_napi_del() while NAPI is still scheduled. This results in a kernel WARN and stack trace, but does not appear to be exploitable for code execution or privilege escalation.
Affected code
The vulnerability is in the lan78xx USB Ethernet driver's disconnect path. The function lan78xx_disconnect() in the driver calls netif_napi_del() explicitly, which is redundant because unregister_netdev() already handles NAPI teardown. The patch removes this call from the disconnect path.
What the fix does
The patch removes the redundant netif_napi_del() call from the lan78xx_disconnect() function. Since unregister_netdev() already handles NAPI teardown safely and automatically, the explicit call is unnecessary and triggers a WARN when NAPI is still enabled at disconnect time. By deleting this call, the disconnect path no longer attempts to delete NAPI structures that are still in use, preventing the kernel warning.
Preconditions
- inputPhysical access to a USB port to connect/disconnect a lan78xx-based USB Ethernet device.
- configThe lan78xx driver must be loaded and the device must be active (NAPI enabled) at the time of disconnect.
Generated on May 19, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
3News mentions
0No linked articles in our index yet.