In the Linux kernel, the following vulnerability has been resolved:
net: better track kernel sockets lifetime
While kernel sockets are dismantled during pernet_operations->exit(),
their freeing can be delayed by any tx packets still held in qdisc
or device queues, due to skb_set_owner_w() prior calls.
This then trigger the following warning from ref_tracker_dir_exit() [1]
To fix this, make sure that kernel sockets own a reference on net->passive.
Add sk_net_refcnt_upgrade() helper, used whenever a kernel socket
is converted to a refcounted one.
[1]
[ 136.263918][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at
[ 136.263918][ T35] sk_alloc+0x2b3/0x370
[ 136.263918][ T35] inet6_create+0x6ce/0x10f0
[ 136.263918][ T35] __sock_create+0x4c0/0xa30
[ 136.263918][ T35] inet_ctl_sock_create+0xc2/0x250
[ 136.263918][ T35] igmp6_net_init+0x39/0x390
[ 136.263918][ T35] ops_init+0x31e/0x590
[ 136.263918][ T35] setup_net+0x287/0x9e0
[ 136.263918][ T35] copy_net_ns+0x33f/0x570
[ 136.263918][ T35] create_new_namespaces+0x425/0x7b0
[ 136.263918][ T35] unshare_nsproxy_namespaces+0x124/0x180
[ 136.263918][ T35] ksys_unshare+0x57d/0xa70
[ 136.263918][ T35] __x64_sys_unshare+0x38/0x40
[ 136.263918][ T35] do_syscall_64+0xf3/0x230
[ 136.263918][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f
[ 136.263918][ T35]
[ 136.343488][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at
[ 136.343488][ T35] sk_alloc+0x2b3/0x370
[ 136.343488][ T35] inet6_create+0x6ce/0x10f0
[ 136.343488][ T35] __sock_create+0x4c0/0xa30
[ 136.343488][ T35] inet_ctl_sock_create+0xc2/0x250
[ 136.343488][ T35] ndisc_net_init+0xa7/0x2b0
[ 136.343488][ T35] ops_init+0x31e/0x590
[ 136.343488][ T35] setup_net+0x287/0x9e0
[ 136.343488][ T35] copy_net_ns+0x33f/0x570
[ 136.343488][ T35] create_new_namespaces+0x425/0x7b0
[ 136.343488][ T35] unshare_nsproxy_namespaces+0x124/0x180
[ 136.343488][ T35] ksys_unshare+0x57d/0xa70
[ 136.343488][ T35] __x64_sys_unshare+0x38/0x40
[ 136.343488][ T35] do_syscall_64+0xf3/0x230
[ 136.343488][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f
net: better track kernel sockets lifetime
While kernel sockets are dismantled during pernet_operations->exit(),
their freeing can be delayed by any tx packets still held in qdisc
or device queues, due to skb_set_owner_w() prior calls.
This then trigger the following warning from ref_tracker_dir_exit() [1]
To fix this, make sure that kernel sockets own a reference on net->passive.
Add sk_net_refcnt_upgrade() helper, used whenever a kernel socket
is converted to a refcounted one.
[1]
[ 136.263918][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at
[ 136.263918][ T35] sk_alloc+0x2b3/0x370
[ 136.263918][ T35] inet6_create+0x6ce/0x10f0
[ 136.263918][ T35] __sock_create+0x4c0/0xa30
[ 136.263918][ T35] inet_ctl_sock_create+0xc2/0x250
[ 136.263918][ T35] igmp6_net_init+0x39/0x390
[ 136.263918][ T35] ops_init+0x31e/0x590
[ 136.263918][ T35] setup_net+0x287/0x9e0
[ 136.263918][ T35] copy_net_ns+0x33f/0x570
[ 136.263918][ T35] create_new_namespaces+0x425/0x7b0
[ 136.263918][ T35] unshare_nsproxy_namespaces+0x124/0x180
[ 136.263918][ T35] ksys_unshare+0x57d/0xa70
[ 136.263918][ T35] __x64_sys_unshare+0x38/0x40
[ 136.263918][ T35] do_syscall_64+0xf3/0x230
[ 136.263918][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f
[ 136.263918][ T35]
[ 136.343488][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at
[ 136.343488][ T35] sk_alloc+0x2b3/0x370
[ 136.343488][ T35] inet6_create+0x6ce/0x10f0
[ 136.343488][ T35] __sock_create+0x4c0/0xa30
[ 136.343488][ T35] inet_ctl_sock_create+0xc2/0x250
[ 136.343488][ T35] ndisc_net_init+0xa7/0x2b0
[ 136.343488][ T35] ops_init+0x31e/0x590
[ 136.343488][ T35] setup_net+0x287/0x9e0
[ 136.343488][ T35] copy_net_ns+0x33f/0x570
[ 136.343488][ T35] create_new_namespaces+0x425/0x7b0
[ 136.343488][ T35] unshare_nsproxy_namespaces+0x124/0x180
[ 136.343488][ T35] ksys_unshare+0x57d/0xa70
[ 136.343488][ T35] __x64_sys_unshare+0x38/0x40
[ 136.343488][ T35] do_syscall_64+0xf3/0x230
[ 136.343488][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f
Metrics
Affected Vendors & Products
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 28 Aug 2025 14:45:00 +0000
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Wed, 20 Aug 2025 18:00:00 +0000
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Fri, 28 Mar 2025 14:00:00 +0000
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Metrics |
threat_severity
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cvssV3_1
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Thu, 27 Mar 2025 15:15:00 +0000
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Description | In the Linux kernel, the following vulnerability has been resolved: net: better track kernel sockets lifetime While kernel sockets are dismantled during pernet_operations->exit(), their freeing can be delayed by any tx packets still held in qdisc or device queues, due to skb_set_owner_w() prior calls. This then trigger the following warning from ref_tracker_dir_exit() [1] To fix this, make sure that kernel sockets own a reference on net->passive. Add sk_net_refcnt_upgrade() helper, used whenever a kernel socket is converted to a refcounted one. [1] [ 136.263918][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at [ 136.263918][ T35] sk_alloc+0x2b3/0x370 [ 136.263918][ T35] inet6_create+0x6ce/0x10f0 [ 136.263918][ T35] __sock_create+0x4c0/0xa30 [ 136.263918][ T35] inet_ctl_sock_create+0xc2/0x250 [ 136.263918][ T35] igmp6_net_init+0x39/0x390 [ 136.263918][ T35] ops_init+0x31e/0x590 [ 136.263918][ T35] setup_net+0x287/0x9e0 [ 136.263918][ T35] copy_net_ns+0x33f/0x570 [ 136.263918][ T35] create_new_namespaces+0x425/0x7b0 [ 136.263918][ T35] unshare_nsproxy_namespaces+0x124/0x180 [ 136.263918][ T35] ksys_unshare+0x57d/0xa70 [ 136.263918][ T35] __x64_sys_unshare+0x38/0x40 [ 136.263918][ T35] do_syscall_64+0xf3/0x230 [ 136.263918][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 136.263918][ T35] [ 136.343488][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at [ 136.343488][ T35] sk_alloc+0x2b3/0x370 [ 136.343488][ T35] inet6_create+0x6ce/0x10f0 [ 136.343488][ T35] __sock_create+0x4c0/0xa30 [ 136.343488][ T35] inet_ctl_sock_create+0xc2/0x250 [ 136.343488][ T35] ndisc_net_init+0xa7/0x2b0 [ 136.343488][ T35] ops_init+0x31e/0x590 [ 136.343488][ T35] setup_net+0x287/0x9e0 [ 136.343488][ T35] copy_net_ns+0x33f/0x570 [ 136.343488][ T35] create_new_namespaces+0x425/0x7b0 [ 136.343488][ T35] unshare_nsproxy_namespaces+0x124/0x180 [ 136.343488][ T35] ksys_unshare+0x57d/0xa70 [ 136.343488][ T35] __x64_sys_unshare+0x38/0x40 [ 136.343488][ T35] do_syscall_64+0xf3/0x230 [ 136.343488][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f | |
Title | net: better track kernel sockets lifetime | |
References |
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-08-28T14:42:47.342Z
Reserved: 2024-12-29T08:45:45.782Z
Link: CVE-2025-21884

No data.

Status : Awaiting Analysis
Published: 2025-03-27T15:15:56.313
Modified: 2025-08-28T15:15:46.113
Link: CVE-2025-21884


No data.