CVE-2025-39925 (GCVE-0-2025-39925)
Vulnerability from cvelistv5
Published
2025-10-01 08:07
Modified
2025-10-01 08:07
Severity ?
VLAI Severity ?
EPSS score ?
Summary
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]
References
Impacted products
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"net/can/j1939/j1939-priv.h",
"net/can/j1939/main.c",
"net/can/j1939/socket.c"
],
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"versions": [
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: j1939: implement NETDEV_UNREGISTER notification handler\n\nsyzbot is reporting\n\n unregister_netdevice: waiting for vcan0 to become free. Usage count = 2\n\nproblem, for j1939 protocol did not have NETDEV_UNREGISTER notification\nhandler for undoing changes made by j1939_sk_bind().\n\nCommit 25fe97cb7620 (\"can: j1939: move j1939_priv_put() into sk_destruct\ncallback\") expects that a call to j1939_priv_put() can be unconditionally\ndelayed until j1939_sk_sock_destruct() is called. But we need to call\nj1939_priv_put() against an extra ref held by j1939_sk_bind() call\n(as a part of undoing changes made by j1939_sk_bind()) as soon as\nNETDEV_UNREGISTER notification fires (i.e. before j1939_sk_sock_destruct()\nis called via j1939_sk_release()). Otherwise, the extra ref on \"struct\nj1939_priv\" held by j1939_sk_bind() call prevents \"struct net_device\" from\ndropping the usage count to 1; making it impossible for\nunregister_netdevice() to continue.\n\n[mkl: remove space in front of label]"
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"url": "https://git.kernel.org/stable/c/7fcbe5b2c6a4b5407bf2241fdb71e0a390f6ab9a"
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"title": "can: j1939: implement NETDEV_UNREGISTER notification handler",
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"dateReserved": "2025-04-16T07:20:57.147Z",
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