From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C58123F0776 for ; Fri, 8 May 2026 14:26:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778250379; cv=none; b=tchoGq+1kofEvrceQqULMu0xLKqc/kzQYH26oKGtWio/OlSpcr1d481gpK5B9toc5owNzLajqGjicKhpDFNn31wvgy7mUGuptJkqvua/59qJXt2AcEh0wyFi42IVmox/vmQ/7p6FRAMESoWwjFf8MB7nUT0KZNzevZKycMoyGag= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778250379; c=relaxed/simple; bh=v3Z8spD8npggcaNcZoZwhu0aoF/omkXtLJaMC18qeIc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=VVAvuUQn/UZCsYAwV6UjJQ2hDQd+kfJjXU70kkziek8sI/Dgqn/WluBxikLnVJ8501Ao1YsZMU78Wk+bvNzpdNT9zzsSTk2I2fTXlY9NQeOoZ7MOZu7AIy5QFKFBwNAEVHaXfgFUKJcQqKHUx0UGcDLU6yKQ09heExoTBy2UnJs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=HxkeadLY; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="HxkeadLY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2216AC2BCB0; Fri, 8 May 2026 14:26:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778250379; bh=v3Z8spD8npggcaNcZoZwhu0aoF/omkXtLJaMC18qeIc=; h=From:To:Cc:Subject:Date:Reply-To:From; b=HxkeadLYH1/UxVxTf3wzi74718A6JfBkZlmYiuHwzpSxYWiKfrkYm6K9ACdJOJ3o+ +Bzm7U/b7hlFz920BLfj5utoKaJmlP44R3VHqAFXQjfq8SAErnKsC9oNYAQsPRt/D/ L7h612YA4RGuYJBWirdmCB15+ypqpiUgFJpAIqXI= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-43421: usb: gadget: f_ncm: Fix net_device lifecycle with device_move Date: Fri, 8 May 2026 16:22:30 +0200 Message-ID: <2026050847-CVE-2026-43421-82b4@gregkh> X-Mailer: git-send-email 2.54.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3570; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=XxMNUhQ8F2v+ieKLslnJfFFOF0DokVuiBhccs5SVEmw=; b=owGbwMvMwCRo6H6F97bub03G02pJDJl/P1a/juut/eSV4OjJGHA1atvLN/87HO5Zb+7e31a6T 5TVbkpqRywLgyATg6yYIsuXbTxH91ccUvQytD0NM4eVCWQIAxenAEzkaD3DgvXcnB4Viw2PKO3a uszdeZWtbdc5LoYFFwLDijIF++TXrY/7+jhCq1RFrF0LAA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_ncm: Fix net_device lifecycle with device_move The network device outlived its parent gadget device during disconnection, resulting in dangling sysfs links and null pointer dereference problems. A prior attempt to solve this by removing SET_NETDEV_DEV entirely [1] was reverted due to power management ordering concerns and a NO-CARRIER regression. A subsequent attempt to defer net_device allocation to bind [2] broke 1:1 mapping between function instance and network device, making it impossible for configfs to report the resolved interface name. This results in a regression where the DHCP server fails on pmOS. Use device_move to reparent the net_device between the gadget device and /sys/devices/virtual/ across bind/unbind cycles. This preserves the network interface across USB reconnection, allowing the DHCP server to retain their binding. Introduce gether_attach_gadget()/gether_detach_gadget() helpers and use __free(detach_gadget) macro to undo attachment on bind failure. The bind_count ensures device_move executes only on the first bind. [1] https://lore.kernel.org/lkml/f2a4f9847617a0929d62025748384092e5f35cce.camel@crapouillou.net/ [2] https://lore.kernel.org/linux-usb/795ea759-7eaf-4f78-81f4-01ffbf2d7961@ixit.cz/ The Linux kernel CVE team has assigned CVE-2026-43421 to this issue. Affected and fixed versions =========================== Issue introduced in 3.11 with commit 40d133d7f542616cf9538508a372306e626a16e9 and fixed in 6.12.78 with commit 93f116c3393a22acab96ad1bef12b2572eb80ca4 Issue introduced in 3.11 with commit 40d133d7f542616cf9538508a372306e626a16e9 and fixed in 6.18.19 with commit e584cb58a2ea7ff4d3a4bc43d5ca512ed3ecb77d Issue introduced in 3.11 with commit 40d133d7f542616cf9538508a372306e626a16e9 and fixed in 6.19.9 with commit 85acaba2f42b557499bab3608307f17bf13beb69 Issue introduced in 3.11 with commit 40d133d7f542616cf9538508a372306e626a16e9 and fixed in 7.0 with commit ec35c1969650e7cb6c8a91020e568ed46e3551b0 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-2026-43421 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/usb/gadget/function/f_ncm.c drivers/usb/gadget/function/u_ether.c drivers/usb/gadget/function/u_ether.h drivers/usb/gadget/function/u_ncm.h 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/93f116c3393a22acab96ad1bef12b2572eb80ca4 https://git.kernel.org/stable/c/e584cb58a2ea7ff4d3a4bc43d5ca512ed3ecb77d https://git.kernel.org/stable/c/85acaba2f42b557499bab3608307f17bf13beb69 https://git.kernel.org/stable/c/ec35c1969650e7cb6c8a91020e568ed46e3551b0