linux-cve-announce - CVE-2025-40164: usbnet: Fix using smp_processor

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Message-ID: <2025111227-CVE-2025-40164-cbee@gregkh>
Date: Wed, 12 Nov 2025 19:26:30 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40164: usbnet: Fix using smp_processor_id() in preemptible code warnings

From: Greg Kroah-Hartman <gregkh@...nel.org>

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/core/dev_ioctl.c:572
 dev_ioctl+0x223/0x10e0 net/core/dev_ioctl.c:821
 sock_do_ioctl+0x19d/0x280 net/socket.c:1204
 sock_ioctl+0x42f/0x6a0 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

For historical and portability reasons, the netif_rx() is usually
run in the softirq or interrupt context, this commit therefore add
local_bh_disable/enable() protection in the usbnet_resume_rx().

The Linux kernel CVE team has assigned CVE-2025-40164 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 4.7 with commit 43daa96b166c3cf5ff30dfac0c5efa2620e4beab and fixed in 6.17.5 with commit 0134c7bff14bd50314a4f92b182850ddfc38e255
	Issue introduced in 4.7 with commit 43daa96b166c3cf5ff30dfac0c5efa2620e4beab and fixed in 6.18-rc2 with commit 327cd4b68b4398b6c24f10eb2b2533ffbfc10185

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-40164
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/net/usb/usbnet.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/0134c7bff14bd50314a4f92b182850ddfc38e255
	https://git.kernel.org/stable/c/327cd4b68b4398b6c24f10eb2b2533ffbfc10185