CVE-2025-39925 - can: j1939: implement NETDEV_UNREGISTER notification handler

CVE-2025-39925 - can: j1939: implement NETDEV_UNREGISTER notification handler

https://cvefeed.io/rssfeed/latest.atom / Wed, 10/01/2025 - 11:41
CVE ID : CVE-2025-39925
Published : Oct. 1, 2025, 8:15 a.m. | 1 hour, 17 minutes ago
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]
Severity: 0.0 | NA
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