{ "schema_version": "1.6.1", "id": "RPI-CVE-2024-46858", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2024-46858" ], "published": "2024-09-27T12:43:58Z", "summary": "mptcp: pm: Fix uaf in __timer_delete_sync", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: pm: Fix uaf in __timer_delete_sync\n\nThere are two paths to access mptcp_pm_del_add_timer, result in a race\ncondition:\n\n CPU1\t\t\t\tCPU2\n ==== ====\n net_rx_action\n napi_poll netlink_sendmsg\n __napi_poll netlink_unicast\n process_backlog netlink_unicast_kernel\n __netif_receive_skb genl_rcv\n __netif_receive_skb_one_core netlink_rcv_skb\n NF_HOOK genl_rcv_msg\n ip_local_deliver_finish genl_family_rcv_msg\n ip_protocol_deliver_rcu genl_family_rcv_msg_doit\n tcp_v4_rcv mptcp_pm_nl_flush_addrs_doit\n tcp_v4_do_rcv mptcp_nl_remove_addrs_list\n tcp_rcv_established mptcp_pm_remove_addrs_and_subflows\n tcp_data_queue remove_anno_list_by_saddr\n mptcp_incoming_options mptcp_pm_del_add_timer\n mptcp_pm_del_add_timer kfree(entry)\n\nIn remove_anno_list_by_saddr(running on CPU2), after leaving the critical\nzone protected by \"pm.lock\", the entry will be released, which leads to the\noccurrence of uaf in the mptcp_pm_del_add_timer(running on CPU1).\n\nKeeping a reference to add_timer inside the lock, and calling\nsk_stop_timer_sync() with this reference, instead of \"entry->add_timer\".\n\nMove list_del(&entry->list) to mptcp_pm_del_add_timer and inside the pm lock,\ndo not directly access any members of the entry outside the pm lock, which\ncan avoid similar \"entry->x\" uaf.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:N/AC:H/PR:N/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+rpt2", "1:6.1.47-1+rpt4", "1:6.1.54-1+rpt2", "1:6.1.58-1+rpt2", "1:6.1.63-1+rpt1", "1:6.1.73-1+rpt1", "1:6.6.20-1+rpt1", "1:6.6.28-1+rpt1", "1:6.6.31-1+rpt1", 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"2026-08-05T11:52:36Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 8.1, "cvss_v3_severity": "High", "scenario": "AV:N - The use-after-free dereference occurs in the TCP/MPTCP receive path (`mptcp_incoming_options()` \u2192 `mptcp_pm_del_add_timer()`), driven entirely by an `ADD_ADDR` echo option in a TCP segment sent by the remote MPTCP peer, executed in softirq context. Any internet-facing MPTCP-enabled endpoint (server or Android/mobile client with a `signal` endpoint configured) processes this attacker-supplied option, so the vulnerable code is reached over the network.\nAC:H - The remote peer can hammer the racing side without limit by repeatedly sending ADD_ADDR echoes, but the freeing side must be executed concurrently by the local path manager (netlink FLUSH_ADDRS/DEL_ADDR, e.g. mptcpd reacting to an interface change), which is timing the attacker cannot influence. Winning that window is a condition beyond the remote attacker's control.\nPR:N - The attacker-controlled side requires only being the peer of an established MPTCP connection to a listening service \u2014 no account, credentials, or privileges on the target are needed, and the ADD_ADDR echo is accepted as part of normal protocol processing once the connection is fully established.\nUI:N - No victim action is required; the ADD_ADDR announcement and the peer's echo are automatic protocol behaviour, and the concurrent endpoint flush is performed by a background path-manager daemon rather than an interactive user.\nS:U - The corruption is confined to kernel heap memory within the same security authority; there is no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - The freed `mptcp_pm_add_entry` lives in a generic kmalloc cache and can be reclaimed with attacker-shaped data, and the subsequent `timer_delete_sync()`/`__sock_put()` on that stale object gives a foothold for arbitrary kernel memory disclosure, as is standard for slab use-after-free.\nI:H - `__timer_delete_sync()` on the reclaimed object acts on attacker-influenced `timer->flags` and can perform an hlist unlink write (`*pprev = next; next->pprev = pprev`), and the spurious `__sock_put()` underflows the socket refcount \u2014 both yield write primitives leveragable for control-flow hijack. The same missing-lock defect also permits a double `kfree()` of the entry from two concurrent netlink removals.\nA:H - The use-after-free reliably produces a KASAN slab-use-after-free / kernel oops in softirq context (as reported by syzbot), and the resulting timer-base list corruption or socket refcount underflow causes a kernel panic." } } }