{ "schema_version": "1.6.1", "id": "RPI-CVE-2023-53673", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2023-53673" ], "published": "2025-10-07T15:23:56Z", "summary": "Bluetooth: hci_event: call disconnect callback before deleting conn", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_event: call disconnect callback before deleting conn\n\nIn hci_cs_disconnect, we do hci_conn_del even if disconnection failed.\n\nISO, L2CAP and SCO connections refer to the hci_conn without\nhci_conn_get, so disconn_cfm must be called so they can clean up their\nconn, otherwise use-after-free occurs.\n\nISO:\n==========================================================\niso_sock_connect:880: sk 00000000eabd6557\niso_connect_cis:356: 70:1a:b8:98:ff:a2 -> 28:3d:c2:4a:7e:da\n...\niso_conn_add:140: hcon 000000001696f1fd conn 00000000b6251073\nhci_dev_put:1487: hci0 orig refcnt 17\n__iso_chan_add:214: conn 00000000b6251073\niso_sock_clear_timer:117: sock 00000000eabd6557 state 3\n...\nhci_rx_work:4085: hci0 Event packet\nhci_event_packet:7601: hci0: event 0x0f\nhci_cmd_status_evt:4346: hci0: opcode 0x0406\nhci_cs_disconnect:2760: hci0: status 0x0c\nhci_sent_cmd_data:3107: hci0 opcode 0x0406\nhci_conn_del:1151: hci0 hcon 000000001696f1fd handle 2560\nhci_conn_unlink:1102: hci0: hcon 000000001696f1fd\nhci_conn_drop:1451: hcon 00000000d8521aaf orig refcnt 2\nhci_chan_list_flush:2780: hcon 000000001696f1fd\nhci_dev_put:1487: hci0 orig refcnt 21\nhci_dev_put:1487: hci0 orig refcnt 20\nhci_req_cmd_complete:3978: opcode 0x0406 status 0x0c\n... ...\niso_sock_sendmsg:1098: sock 00000000dea5e2e0, sk 00000000eabd6557\nBUG: kernel NULL pointer dereference, address: 0000000000000668\nPGD 0 P4D 0\nOops: 0000 [#1] PREEMPT SMP PTI\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014\nRIP: 0010:iso_sock_sendmsg (net/bluetooth/iso.c:1112) bluetooth\n==========================================================\n\nL2CAP:\n==================================================================\nhci_cmd_status_evt:4359: hci0: opcode 0x0406\nhci_cs_disconnect:2760: hci0: status 0x0c\nhci_sent_cmd_data:3085: hci0 opcode 0x0406\nhci_conn_del:1151: hci0 hcon ffff88800c999000 handle 3585\nhci_conn_unlink:1102: hci0: hcon ffff88800c999000\nhci_chan_list_flush:2780: hcon ffff88800c999000\nhci_chan_del:2761: hci0 hcon ffff88800c999000 chan ffff888018ddd280\n...\nBUG: KASAN: slab-use-after-free in hci_send_acl+0x2d/0x540 [bluetooth]\nRead of size 8 at addr ffff888018ddd298 by task bluetoothd/1175\n\nCPU: 0 PID: 1175 Comm: bluetoothd Tainted: G E 6.4.0-rc4+ #2\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014\nCall Trace:\n \n dump_stack_lvl+0x5b/0x90\n print_report+0xcf/0x670\n ? __virt_addr_valid+0xf8/0x180\n ? hci_send_acl+0x2d/0x540 [bluetooth]\n kasan_report+0xa8/0xe0\n ? hci_send_acl+0x2d/0x540 [bluetooth]\n hci_send_acl+0x2d/0x540 [bluetooth]\n ? __pfx___lock_acquire+0x10/0x10\n l2cap_chan_send+0x1fd/0x1300 [bluetooth]\n ? l2cap_sock_sendmsg+0xf2/0x170 [bluetooth]\n ? __pfx_l2cap_chan_send+0x10/0x10 [bluetooth]\n ? lock_release+0x1d5/0x3c0\n ? mark_held_locks+0x1a/0x90\n l2cap_sock_sendmsg+0x100/0x170 [bluetooth]\n sock_write_iter+0x275/0x280\n ? __pfx_sock_write_iter+0x10/0x10\n ? __pfx___lock_acquire+0x10/0x10\n do_iter_readv_writev+0x176/0x220\n ? __pfx_do_iter_readv_writev+0x10/0x10\n ? find_held_lock+0x83/0xa0\n ? selinux_file_permission+0x13e/0x210\n do_iter_write+0xda/0x340\n vfs_writev+0x1b4/0x400\n ? __pfx_vfs_writev+0x10/0x10\n ? __seccomp_filter+0x112/0x750\n ? populate_seccomp_data+0x182/0x220\n ? __fget_light+0xdf/0x100\n ? do_writev+0x19d/0x210\n do_writev+0x19d/0x210\n ? __pfx_do_writev+0x10/0x10\n ? mark_held_locks+0x1a/0x90\n do_syscall_64+0x60/0x90\n ? lockdep_hardirqs_on_prepare+0x149/0x210\n ? do_syscall_64+0x6c/0x90\n ? lockdep_hardirqs_on_prepare+0x149/0x210\n entry_SYSCALL_64_after_hwframe+0x72/0xdc\nRIP: 0033:0x7ff45cb23e64\nCode: 15 d1 1f 0d 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 80 3d 9d a7 0d 00 00 74 13 b8 14 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 48 83 ec 28 89 54 24 1c 48 89\nRSP: 002b:00007fff21ae09b8 EFLAGS: 00000202 ORIG_RAX: 0000000000000014\nRAX: ffffffffffffffda RBX: \n---truncated---", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.21-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi1-rpi-v6", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v8", "binary_version": "1:6.1.21-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.1.21-1+rpt1": { "linux_commit": "0afb5e98488aed7017b9bf321b575d0177feb7ed", "upstream_version": "6.1.21", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.42" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2023-53673" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/1ecf6dc2676ead4b927c50b1be0851fa4d756574" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/59bd1e476bbc7bc6dff3c61bba787095a4839796" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/093a07052406b363b1b2ab489e17dbadaf3e509b" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/7f7cfcb6f0825652973b780f248603e23f16ee90" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T11:24:39Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 8.8, "cvss_v3_severity": "High", "scenario": "AV:A - The bug is in the Bluetooth HCI event handler, triggered by a Command Status event for HCI_Disconnect whose failure status is induced by a peer device terminating the link concurrently with the host's disconnect. Exploitation requires only Bluetooth radio proximity to the target (phones, cars, headsets, laptops), which is CVSS Adjacent.\nAC:L - The attacker controls both sides of the race: closing the last L2CAP channel forces hcon->disc_timeout=0 and an immediate host Disconnect, and the attacker then tears down the link-layer connection at that moment so the controller answers Unknown Connection Identifier/Command Disallowed. The attempt costs nothing and can be repeated indefinitely by reconnecting.\nPR:N - No credentials or pairing are required \u2014 an L2CAP/ISO connection reaches l2cap_conn_add/iso_conn_add before authentication, and no capability check exists on the path. The attacker needs no account or privilege on the target system.\nUI:N - The dangling l2cap_conn->hchan and iso_conn->hcon are used by ordinary background traffic \u2014 the reported crash occurred in bluetoothd's normal write path \u2014 with no victim action needed. The attacker can also trigger the use itself via further protocol activity.\nS:U - The freed objects and the resulting corruption are entirely within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The freed hci_chan lives in the generic kmalloc-64 cache and hci_send_acl dereferences chan->conn->hdev straight out of it, so a groomed reallocation yields a controlled pointer read of arbitrary kernel memory. Per kernel guidance, use-after-free is scored High confidentiality.\nI:H - Beyond the read primitive, hci_queue_acl writes skb list pointers into the freed object's data_q and later code operates on the forged hci_conn, giving heap-spray-driven write and control-flow influence. Use-after-free of a sprayable kmalloc object is scored High integrity.\nA:H - The bug reproduces as a KASAN slab-use-after-free in hci_send_acl and as a NULL pointer dereference oops in iso_sock_sendmsg, both fatal to the kernel context. Any kernel oops/panic is High availability." } } }