{"id":"DEBIAN-CVE-2025-21678","details":"In the Linux kernel, the following vulnerability has been resolved:  gtp: Destroy device along with udp socket's netns dismantle.  gtp_newlink() links the device to a list in dev_net(dev) instead of src_net, where a udp tunnel socket is created.  Even when src_net is removed, the device stays alive on dev_net(dev). Then, removing src_net triggers the splat below. [0]  In this example, gtp0 is created in ns2, and the udp socket is created in ns1.    ip netns add ns1   ip netns add ns2   ip -n ns1 link add netns ns2 name gtp0 type gtp role sgsn   ip netns del ns1  Let's link the device to the socket's netns instead.  Now, gtp_net_exit_batch_rtnl() needs another netdev iteration to remove all gtp devices in the netns.  [0]: ref_tracker: net notrefcnt@000000003d6e7d05 has 1/2 users at      sk_alloc (./include/net/net_namespace.h:345 net/core/sock.c:2236)      inet_create (net/ipv4/af_inet.c:326 net/ipv4/af_inet.c:252)      __sock_create (net/socket.c:1558)      udp_sock_create4 (net/ipv4/udp_tunnel_core.c:18)      gtp_create_sock (./include/net/udp_tunnel.h:59 drivers/net/gtp.c:1423)      gtp_create_sockets (drivers/net/gtp.c:1447)      gtp_newlink (drivers/net/gtp.c:1507)      rtnl_newlink (net/core/rtnetlink.c:3786 net/core/rtnetlink.c:3897 net/core/rtnetlink.c:4012)      rtnetlink_rcv_msg (net/core/rtnetlink.c:6922)      netlink_rcv_skb (net/netlink/af_netlink.c:2542)      netlink_unicast (net/netlink/af_netlink.c:1321 net/netlink/af_netlink.c:1347)      netlink_sendmsg (net/netlink/af_netlink.c:1891)      ____sys_sendmsg (net/socket.c:711 net/socket.c:726 net/socket.c:2583)      ___sys_sendmsg (net/socket.c:2639)      __sys_sendmsg (net/socket.c:2669)      do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)  WARNING: CPU: 1 PID: 60 at lib/ref_tracker.c:179 ref_tracker_dir_exit (lib/ref_tracker.c:179) Modules linked in: CPU: 1 UID: 0 PID: 60 Comm: kworker/u16:2 Not tainted 6.13.0-rc5-00147-g4c1224501e9d #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Workqueue: netns cleanup_net RIP: 0010:ref_tracker_dir_exit (lib/ref_tracker.c:179) Code: 00 00 00 fc ff df 4d 8b 26 49 bd 00 01 00 00 00 00 ad de 4c 39 f5 0f 85 df 00 00 00 48 8b 74 24 08 48 89 df e8 a5 cc 12 02 90 \u003c0f\u003e 0b 90 48 8d 6b 44 be 04 00 00 00 48 89 ef e8 80 de 67 ff 48 89 RSP: 0018:ff11000009a07b60 EFLAGS: 00010286 RAX: 0000000000002bd3 RBX: ff1100000f4e1aa0 RCX: 1ffffffff0e40ac6 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8423ee3c RBP: ff1100000f4e1af0 R08: 0000000000000001 R09: fffffbfff0e395ae R10: 0000000000000001 R11: 0000000000036001 R12: ff1100000f4e1af0 R13: dead000000000100 R14: ff1100000f4e1af0 R15: dffffc0000000000 FS:  0000000000000000(0000) GS:ff1100006ce80000(0000) knlGS:0000000000000000 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9b2464bd98 CR3: 0000000005286005 CR4: 0000000000771ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400 PKRU: 55555554 Call Trace:  \u003cTASK\u003e  ? __warn (kernel/panic.c:748)  ? ref_tracker_dir_exit (lib/ref_tracker.c:179)  ? report_bug (lib/bug.c:201 lib/bug.c:219)  ? handle_bug (arch/x86/kernel/traps.c:285)  ? exc_invalid_op (arch/x86/kernel/traps.c:309 (discriminator 1))  ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:621)  ? _raw_spin_unlock_irqrestore (./arch/x86/include/asm/irqflags.h:42 ./arch/x86/include/asm/irqflags.h:97 ./arch/x86/include/asm/irqflags.h:155 ./include/linux/spinlock_api_smp.h:151 kernel/locking/spinlock.c:194)  ? ref_tracker_dir_exit (lib/ref_tracker.c:179)  ? __pfx_ref_tracker_dir_exit (lib/ref_tracker.c:158)  ? kfree (mm/slub.c:4613 mm/slub.c:4761)  net_free (net/core/net_namespace.c:476 net/core/net_namespace.c:467)  cleanup_net (net/core/net_namespace.c:664 (discriminator 3))  process_one_work (kernel/workqueue.c:3229)  worker_thread (kernel/workqueue.c:3304 kernel/workqueue.c:3391 ---truncated---","modified":"2026-09-01T16:06:09.597667890Z","published":"2025-01-31T12:15:28.970Z","upstream":["CVE-2025-21678"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2025-21678"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.128-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-21678.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.11-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-21678.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.11-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-21678.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}