CVE-2025-40164

/// Technical description

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

usbnet: Fix using smp_processor_id() in preemptible code warnings

Syzbot reported the following warning:

BUG: using smp_processor_id() in preemptible [00000000] code: dhcpcd/2879

caller is usbnet_skb_return+0x74/0x490 drivers/net/usb/usbnet.c:331

CPU: 1 UID: 0 PID: 2879 Comm: dhcpcd Not tainted 6.15.0-rc4-syzkaller-00098-g615dca38c2ea #0 PREEMPT(voluntary)

Call Trace:

<TASK>

__dump_stack lib/dump_stack.c:94 [inline]

dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120

check_preemption_disabled+0xd0/0xe0 lib/smp_processor_id.c:49

usbnet_skb_return+0x74/0x490 drivers/net/usb/usbnet.c:331

usbnet_resume_rx+0x4b/0x170 drivers/net/usb/usbnet.c:708

usbnet_change_mtu+0x1be/0x220 drivers/net/usb/usbnet.c:417

__dev_set_mtu net/core/dev.c:9443 [inline]

netif_set_mtu_ext+0x369/0x5c0 net/core/dev.c:9496

netif_set_mtu+0xb0/0x160 net/core/dev.c:9520

dev_set_mtu+0xae/0x170 net/core/dev_api.c:247

dev_ifsioc+0xa31/0x18d0 net/c

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References