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]
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2025100124-CVE-2025-39925-bcec@gregkh/T
This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2025:22854 https://access.redhat.com/errata/RHSA-2025:22854
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2025:22865 https://access.redhat.com/errata/RHSA-2025:22865
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.6 Extended Update Support Via RHSA-2025:23789 https://access.redhat.com/errata/RHSA-2025:23789
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.4 Extended Update Support Via RHSA-2026:0173 https://access.redhat.com/errata/RHSA-2026:0173
This issue has been addressed in the following products: Red Hat Enterprise Linux 10.0 Extended Update Support Via RHSA-2026:0271 https://access.redhat.com/errata/RHSA-2026:0271
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions Via RHSA-2026:0537 https://access.redhat.com/errata/RHSA-2026:0537
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:0534 https://access.redhat.com/errata/RHSA-2026:0534
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:0535 https://access.redhat.com/errata/RHSA-2026:0535
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions Via RHSA-2026:0576 https://access.redhat.com/errata/RHSA-2026:0576