CVE-2025-39925

Description

In the Linux kernel, the following vulnerability has been resolved: can: j1939: implement NETDEV_UNREGISTER notification handler syzbot is reporting unregister_netdevice: waiting for vcan0 to become free. Usage count = 2 problem, for j1939 protocol did not have NETDEV_UNREGISTER notification handler for undoing changes made by j1939_sk_bind(). Commit 25fe97cb7620 ("can: j1939: move j1939_priv_put() into sk_destruct callback") expects that a call to j1939_priv_put() can be unconditionally delayed until j1939_sk_sock_destruct() is called. But we need to call j1939_priv_put() against an extra ref held by j1939_sk_bind() call (as a part of undoing changes made by j1939_sk_bind()) as soon as NETDEV_UNREGISTER notification fires (i.e. before j1939_sk_sock_destruct() is called via j1939_sk_release()). Otherwise, the extra ref on "struct j1939_priv" held by j1939_sk_bind() call prevents "struct net_device" from dropping the usage count to 1; making it impossible for unregister_netdevice() to continue. [mkl: remove space in front of label]

Gravité et risque d'exploitation

CVE-2025-39925 obtient un score CVSS de 5.5/10, soit une gravité moyenne. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.15 %, ce qui la place devant 3.5 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions 6.16.8, <=6.1.*, <=6.12.*, 6.6.156, <=6.16.*, <2c88069fac2c792e228e6a4ae71c9b9b5b9a87a6, 5.4, 6.17, 0, <=6.6.*, <da9e8f429139928570407e8f90559b5d46c20262, <76957b618ce729c3bd1e782fbc9d9991af653925, <479d8a2aedcc1db16f14c1a8a9c74b5bdf18b9ac, <4e154cb5e7681c2910e2dfa09f05e3469e333745, 9d71dd0c70099914fcd063135da3c580865e924c, <5.4, <7fcbe5b2c6a4b5407bf2241fdb71e0a390f6ab9a, 5.15.220, <=*, <=5.15.*, 6.12.108, 6.1.187) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/479d8a2aedcc1db16f14c1a8a9c74b5bdf18b9ac
• https://git.kernel.org/stable/c/2c88069fac2c792e228e6a4ae71c9b9b5b9a87a6
• https://git.kernel.org/stable/c/76957b618ce729c3bd1e782fbc9d9991af653925
• https://git.kernel.org/stable/c/4e154cb5e7681c2910e2dfa09f05e3469e333745
• https://git.kernel.org/stable/c/da9e8f429139928570407e8f90559b5d46c20262
• https://git.kernel.org/stable/c/7fcbe5b2c6a4b5407bf2241fdb71e0a390f6ab9a