{ "schema_version": "1.6.1", "id": "RPI-CVE-2024-56642", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2024-56642" ], "published": "2024-12-27T15:03:32Z", "summary": "tipc: Fix use-after-free of kernel socket in cleanup_bearer().", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: Fix use-after-free of kernel socket in cleanup_bearer().\n\nsyzkaller reported a use-after-free of UDP kernel socket\nin cleanup_bearer() without repro. [0][1]\n\nWhen bearer_disable() calls tipc_udp_disable(), cleanup\nof the UDP kernel socket is deferred by work calling\ncleanup_bearer().\n\ntipc_exit_net() waits for such works to finish by checking\ntipc_net(net)->wq_count. However, the work decrements the\ncount too early before releasing the kernel socket,\nunblocking cleanup_net() and resulting in use-after-free.\n\nLet's move the decrement after releasing the socket in\ncleanup_bearer().\n\n[0]:\nref_tracker: net notrefcnt@000000009b3d1faf has 1/1 users at\n sk_alloc+0x438/0x608\n inet_create+0x4c8/0xcb0\n __sock_create+0x350/0x6b8\n sock_create_kern+0x58/0x78\n udp_sock_create4+0x68/0x398\n udp_sock_create+0x88/0xc8\n tipc_udp_enable+0x5e8/0x848\n __tipc_nl_bearer_enable+0x84c/0xed8\n tipc_nl_bearer_enable+0x38/0x60\n genl_family_rcv_msg_doit+0x170/0x248\n genl_rcv_msg+0x400/0x5b0\n netlink_rcv_skb+0x1dc/0x398\n genl_rcv+0x44/0x68\n netlink_unicast+0x678/0x8b0\n netlink_sendmsg+0x5e4/0x898\n ____sys_sendmsg+0x500/0x830\n\n[1]:\nBUG: KMSAN: use-after-free in udp_hashslot include/net/udp.h:85 [inline]\nBUG: KMSAN: use-after-free in udp_lib_unhash+0x3b8/0x930 net/ipv4/udp.c:1979\n udp_hashslot include/net/udp.h:85 [inline]\n udp_lib_unhash+0x3b8/0x930 net/ipv4/udp.c:1979\n sk_common_release+0xaf/0x3f0 net/core/sock.c:3820\n inet_release+0x1e0/0x260 net/ipv4/af_inet.c:437\n inet6_release+0x6f/0xd0 net/ipv6/af_inet6.c:489\n __sock_release net/socket.c:658 [inline]\n sock_release+0xa0/0x210 net/socket.c:686\n cleanup_bearer+0x42d/0x4c0 net/tipc/udp_media.c:819\n process_one_work kernel/workqueue.c:3229 [inline]\n process_scheduled_works+0xcaf/0x1c90 kernel/workqueue.c:3310\n worker_thread+0xf6c/0x1510 kernel/workqueue.c:3391\n kthread+0x531/0x6b0 kernel/kthread.c:389\n ret_from_fork+0x60/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:244\n\nUninit was created at:\n slab_free_hook mm/slub.c:2269 [inline]\n slab_free mm/slub.c:4580 [inline]\n kmem_cache_free+0x207/0xc40 mm/slub.c:4682\n net_free net/core/net_namespace.c:454 [inline]\n cleanup_net+0x16f2/0x19d0 net/core/net_namespace.c:647\n process_one_work kernel/workqueue.c:3229 [inline]\n process_scheduled_works+0xcaf/0x1c90 kernel/workqueue.c:3310\n worker_thread+0xf6c/0x1510 kernel/workqueue.c:3391\n kthread+0x531/0x6b0 kernel/kthread.c:389\n ret_from_fork+0x60/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:244\n\nCPU: 0 UID: 0 PID: 54 Comm: kworker/0:2 Not tainted 6.12.0-rc1-00131-gf66ebf37d69c #7 91723d6f74857f70725e1583cba3cf4adc716cfa\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\nWorkqueue: events cleanup_bearer", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.47-1+rpt4" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi3-rpi-2712", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v6", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v8", "binary_version": "1:6.1.47-1+rpt4" } ] }, "database_specific": { "per_version": { "1:6.1.47-1+rpt4": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.120", "compiled_filter": false } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2024-56642" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/4e69457f9dfae67435f3ccf29008768eae860415" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/650ee9a22d7a2de8999fac2d45983597a0c22359" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/d2a4894f238551eae178904e7f45af87577074fd" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/d62d5180c036eeac09f80660edc7a602b369125f" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/d00d4470bf8c4282617a3a10e76b20a9c7e4cffa" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/e48b211c4c59062cb6dd6c2c37c51a7cc235a464" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/6a2fa13312e51a621f652d522d7e2df7066330b6" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T11:52:36Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.8, "cvss_v3_severity": "High", "scenario": "AV:L - The vulnerability is reached through generic netlink (TIPC_NL_BEARER_ENABLE/DISABLE) plus network-namespace teardown, both of which require local access to the machine. A remote TIPC/UDP peer cannot cause bearer teardown or netns destruction, so this is not remotely triggerable.\nAC:L - The attacker controls both sides of the race \u2014 creating/destroying the netns and enabling/disabling up to three UDP bearers, repeatedly and in parallel \u2014 and the post-decrement window contains a sleepable free_percpu() in dst_cache_destroy() that can be stalled with attacker-generated load, so the race can be won reliably by looping.\nPR:L - At the time of this bug the TIPCv2 netlink mutators carried no GENL_ADMIN_PERM flag, so a fully unprivileged local user could enable/disable a UDP bearer (later confirmed and fixed by commit 86b0c540e2ea), and the netns teardown that arms the race is available to any user via unshare -Urn; even with the later gate, CAP_NET_ADMIN is obtainable in a user namespace.\nUI:N - The attacker performs every step itself \u2014 load the module, enable the bearer, tear down the namespace \u2014 with no action required from any other user.\nS:U - The use-after-free corrupts kernel memory and is exploited within the same kernel security authority; no VM, IOMMU, or hypervisor boundary is crossed.\nC:H - The freed struct net is read after free in udp_lib_unhash() (udp table pointer, net_hash_mix), and reallocation of the net_cachep object gives the attacker control over the dereferenced contents, enabling kernel memory disclosure.\nI:H - After the struct net is freed, sock_prot_inuse_add() performs this_cpu_add() through a percpu pointer read from freed memory and udp_lib_unhash() takes a spinlock and does list removal through an attacker-influenceable table pointer, yielding a controlled write primitive suitable for privilege escalation.\nA:H - The use-after-free reliably corrupts the UDP hash slots and dereferences freed netns memory, producing kernel oops/panic (as captured by the KMSAN report), and can be triggered repeatedly by an unprivileged user." } } }