kernel/linux.git/net/bluetooth/rfcomm, branch v6.12.107

Bluetooth: RFCOMM: take rfcomm_mutex for the deferred setup accept

2026-08-27T12:32:03+00:00

commit 43a556b2fd43f2df6dded59c2e26560a27874c24 upstream. rfcomm_sock_recvmsg() completes a deferred setup by calling rfcomm_dlc_accept() without holding any RFCOMM lock: if (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) { rfcomm_dlc_accept(d); return 0; } and rfcomm_dlc_accept() dereferences the session on its first line: struct sock *sk = d->session->sock->sk; Every other path that touches d->session runs under rfcomm_mutex: rfcomm_dlc_open(), rfcomm_dlc_close(), rfcomm_dlc_exists(), rfcomm_dlc_send_rpn(), and the RFCOMM thread through rfcomm_process_sessions(). rfcomm_connect_ind() is even documented as "called under rfcomm_lock()". This call site is the only one that skips it. The RFCOMM_DEFER_SETUP bit looks like it serialises the accept against teardown, since __rfcomm_dlc_close() returns early when it wins the test_and_clear. But rfcomm_recv_disc() forces the state first: d->state = BT_CLOSED; __rfcomm_dlc_close(d, err); and the early return only covers BT_CONNECT, BT_CONFIG, BT_OPEN and BT_CONNECT2. With the state already BT_CLOSED that switch does not match, the bit is never consulted, and __rfcomm_dlc_close() falls through to rfcomm_dlc_unlink(), which sets d->session = NULL. So a remote DISC on a deferred dlc clears the session while leaving RFCOMM_DEFER_SETUP set. The next recvmsg() then passes the test_and_clear and dereferences a NULL session. No timing window is needed: once the DISC has been processed, the dereference is unconditional. Give rfcomm_dlc_accept() the same shape as rfcomm_dlc_open() and rfcomm_dlc_close(): an exported wrapper that takes rfcomm_mutex and re-checks the session, around a __rfcomm_dlc_accept() that the two in-core callers, which already hold the mutex, keep using. Reproduced on a KASAN + PROVE_LOCKING kernel with a BR/EDR peer emulated over /dev/vhci: the peer brings up an ACL link, opens L2CAP on the RFCOMM PSM, starts a session, opens a dlc on a channel bound with BT_DEFER_SETUP, and sends DISC after the socket is accepted. recv() on the accepted socket then hits: Oops: general protection fault KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:rfcomm_dlc_accept+0x54/0x350 Call Trace: rfcomm_sock_recvmsg+0x1cd/0x230 sock_recvmsg+0x166/0x1c0 __sys_recvfrom+0x20d/0x300 0x10 is the offset of sock in struct rfcomm_session. With this patch the same run completes with recv() returning 0 and no report, and lockdep stays quiet, confirming rfcomm_mutex is still taken before lock_sock on this path as it is on the thread side. Fixes: bb23c0ab8246 ("Bluetooth: Add support for deferring RFCOMM connection setup") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Greg Kroah-Hartman

Bluetooth: RFCOMM: Fix session UAF in set_termios

2026-08-03T09:17:22+00:00

commit c783399efc22d035443f1dfbf2a09bf9562aaa5e upstream. rfcomm_tty_set_termios() tests dlc->session without rfcomm_mutex and later passes the pointer to rfcomm_send_rpn(). The latter dereferences both session->initiator and session->sock. Meanwhile, krfcommd can unlink the DLC and free the session while holding rfcomm_mutex. The race can proceed as follows: TTY ioctl task krfcommd -------------- -------- load dlc->session enter rfcomm_send_rpn() lock rfcomm_mutex clear dlc->session free session unlock rfcomm_mutex read session->initiator KASAN reported: BUG: KASAN: slab-use-after-free in rfcomm_send_rpn+0x297/0x2a0 Read of size 4 at addr ffff88810012a850 by task poc/92 Call Trace: rfcomm_send_rpn+0x297/0x2a0 rfcomm_tty_set_termios+0x50d/0x850 tty_set_termios+0x596/0x950 set_termios+0x46a/0x6e0 tty_mode_ioctl+0x152/0xbd0 tty_ioctl+0x915/0x1240 __x64_sys_ioctl+0x134/0x1c0 Allocated by task 92: rfcomm_session_add+0x9e/0x2e0 rfcomm_dlc_open+0x8b1/0xe00 rfcomm_dev_activate+0x85/0x1a0 rfcomm_tty_open+0x90/0x280 Freed by task 68: kfree+0x131/0x3c0 rfcomm_session_del+0x119/0x180 rfcomm_run+0x737/0x4710 Add rfcomm_dlc_send_rpn(), which holds rfcomm_mutex while it verifies that the DLC is still attached and sends the RPN frame. Have the TTY path use the helper and drop its unlocked session check. This keeps the session valid through both the frame construction and socket send. Fixes: 3a5e903c09ae ("[Bluetooth]: Implement RFCOMM remote port negotiation") Cc: stable@vger.kernel.org Signed-off-by: Chengfeng Ye Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Greg Kroah-Hartman

Bluetooth: RFCOMM: validate skb length in MCC handlers

2026-06-19T11:42:20+00:00

[ Upstream commit 23882b828c3c8c51d0c946446a396b10abb3b16b ] The RFCOMM MCC handlers cast skb->data to protocol-specific structs without validating skb->len first. A malicious remote device can send truncated MCC frames and trigger out-of-bounds reads in these handlers. Fix this by using skb_pull_data() to validate and access the required data before dereferencing it. rfcomm_recv_rpn() requires special handling since ETSI TS 07.10 allows 1-byte RPN requests. Handle this by validating only the DLCI byte first, and validating the full struct only when len > 1. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Suggested-by: Muhammad Bilal Signed-off-by: SeungJu Cheon Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin

Bluetooth: RFCOMM: hold listener socket in rfcomm_connect_ind()

2026-06-19T11:42:20+00:00

[ Upstream commit 43c441edacf953b39517a44f5e5e10a93618b226 ] rfcomm_get_sock_by_channel() scans rfcomm_sk_list under the list lock, but returns the selected listener after dropping that lock without taking a reference. rfcomm_connect_ind() then locks the listener, queues a child socket on it, and may notify it after unlocking it. The buggy scenario involves two paths, with each column showing the order within that path: rfcomm_connect_ind(): listener close: 1. Find parent in 1. close() enters rfcomm_get_sock_by_channel() rfcomm_sock_release(). 2. Drop rfcomm_sk_list.lock 2. rfcomm_sock_shutdown() without pinning parent. closes the listener. 3. Call lock_sock(parent) and 3. rfcomm_sock_kill() bt_accept_enqueue(parent, unlinks and puts parent. sk, true). 4. Read parent flags and may 4. parent can be freed. call sk_state_change(). If close wins the race, parent can be freed before rfcomm_connect_ind() reaches lock_sock(), bt_accept_enqueue(), or the deferred-setup callback. Take a reference on the listener before leaving rfcomm_sk_list.lock. After lock_sock() succeeds, recheck that it is still in BT_LISTEN before queueing a child, cache the deferred-setup bit while the parent is locked, and drop the reference after the last parent use. KASAN reported a slab-use-after-free in lock_sock_nested() from rfcomm_connect_ind(), with the freeing stack going through rfcomm_sock_kill() and rfcomm_sock_release(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Zhang Cen Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin

Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del()

2026-06-01T15:46:18+00:00

commit ab1513597c6cf17cd1ad2a21e3b045421b48e022 upstream. bt_accept_dequeue() unlinks a not-yet-accepted child from the parent accept queue and release_sock()s it before returning, so the returned sk has no caller reference and is unlocked. l2cap_sock_cleanup_listen() walks these children on listening-socket close. A concurrent HCI disconnect drives hci_rx_work -> l2cap_conn_del() which runs l2cap_chan_del() + l2cap_sock_kill() and frees the child sk and its l2cap_chan; cleanup_listen() then uses both: BUG: KASAN: slab-use-after-free in l2cap_sock_kill l2cap_sock_kill / l2cap_sock_cleanup_listen / __x64_sys_close Freed by: l2cap_conn_del -> l2cap_sock_close_cb -> l2cap_sock_kill This is distinct from the two fixes already in this area: commit e83f5e24da741 ("Bluetooth: serialize accept_q access") serialises the accept_q list/poll and takes temporary refs inside bt_accept_dequeue(), and CVE-2025-39860 serialises the userspace close()/accept() race by calling cleanup_listen() under lock_sock() in l2cap_sock_release(). Neither covers l2cap_conn_del() running from hci_rx_work, so this UAF still reproduces on current bluetooth/master. Take the reference at the source: bt_accept_dequeue() does sock_hold() while sk is still locked, before release_sock(); callers sock_put(). cleanup_listen() pins the chan with l2cap_chan_hold_unless_zero() under a brief child sk lock (serialising vs l2cap_sock_teardown_cb()), drops it before l2cap_chan_lock(), and skips a duplicate l2cap_sock_kill() on SOCK_DEAD. conn->lock is not taken here: cleanup_listen() runs under the parent sk lock and that would invert conn->lock -> chan->lock -> sk_lock (lockdep). KASAN/SMP: an unprivileged listen/close vs HCI-disconnect race produced 12 use-after-free reports per run before this change; 0, and no lockdep report, over 1600+ raced iterations after it on bluetooth/master. Fixes: 15f02b910562 ("Bluetooth: L2CAP: Add initial code for Enhanced Credit Based Mode") Cc: stable@vger.kernel.org Reported-by: Siwei Zhang Reviewed-by: Siwei Zhang Signed-off-by: Safa Karakuş Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Greg Kroah-Hartman

tty: introduce and use tty_port_tty_vhangup() helper

2026-01-08T09:14:56+00:00

[ Upstream commit 2b5eac0f8c6e79bc152c8804f9f88d16717013ab ] This code (tty_get -> vhangup -> tty_put) is repeated on few places. Introduce a helper similar to tty_port_tty_hangup() (asynchronous) to handle even vhangup (synchronous). And use it on those places. In fact, reuse the tty_port_tty_hangup()'s code and call tty_vhangup() depending on a new bool parameter. Signed-off-by: "Jiri Slaby (SUSE)" Cc: Karsten Keil Cc: David Lin Cc: Johan Hovold Cc: Alex Elder Cc: Oliver Neukum Cc: Marcel Holtmann Cc: Johan Hedberg Cc: Luiz Augusto von Dentz Reviewed-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20250611100319.186924-2-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman Stable-dep-of: 74098cc06e75 ("xhci: dbgtty: fix device unregister: fixup") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

Bluetooth: rfcomm: fix modem control handling

2025-11-13T20:33:55+00:00

commit 91d35ec9b3956d6b3cf789c1593467e58855b03a upstream. The RFCOMM driver confuses the local and remote modem control signals, which specifically means that the reported DTR and RTS state will instead reflect the remote end (i.e. DSR and CTS). This issue dates back to the original driver (and a follow-on update) merged in 2002, which resulted in a non-standard implementation of TIOCMSET that allowed controlling also the TS07.10 IC and DV signals by mapping them to the RI and DCD input flags, while TIOCMGET failed to return the actual state of DTR and RTS. Note that the bogus control of input signals in tiocmset() is just dead code as those flags will have been masked out by the tty layer since 2003. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Johan Hovold Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Greg Kroah-Hartman

Revert "Bluetooth: hci_core: Fix sleeping function called from invalid context"

2025-03-22T19:54:11+00:00

[ Upstream commit ab6ab707a4d060a51c45fc13e3b2228d5f7c0b87 ] This reverts commit 4d94f05558271654670d18c26c912da0c1c15549 which has problems (see [1]) and is no longer needed since 581dd2dc168f ("Bluetooth: hci_event: Fix using rcu_read_(un)lock while iterating") has reworked the code where the original bug has been found. [1] Link: https://lore.kernel.org/linux-bluetooth/877c55ci1r.wl-tiwai@suse.de/T/#t Fixes: 4d94f0555827 ("Bluetooth: hci_core: Fix sleeping function called from invalid context") Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin

Bluetooth: btmtk: Fix failed to send func ctrl for MediaTek devices.

2025-01-17T12:40:39+00:00

[ Upstream commit 67dba2c28fe0af7e25ea1aeade677162ed05310a ] Use usb_autopm_get_interface() and usb_autopm_put_interface() in btmtk_usb_shutdown(), it could send func ctrl after enabling autosuspend. Bluetooth: btmtk_usb_hci_wmt_sync() hci0: Execution of wmt command timed out Bluetooth: btmtk_usb_shutdown() hci0: Failed to send wmt func ctrl (-110) Fixes: 5c5e8c52e3ca ("Bluetooth: btmtk: move btusb_mtk_[setup, shutdown] to btmtk.c") Signed-off-by: Chris Lu Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin

Bluetooth: hci_core: Fix sleeping function called from invalid context

2025-01-09T12:33:46+00:00

[ Upstream commit 4d94f05558271654670d18c26c912da0c1c15549 ] This reworks hci_cb_list to not use mutex hci_cb_list_lock to avoid bugs like the bellow: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:585 in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 5070, name: kworker/u9:2 preempt_count: 0, expected: 0 RCU nest depth: 1, expected: 0 4 locks held by kworker/u9:2/5070: #0: ffff888015be3948 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3229 [inline] #0: ffff888015be3948 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_scheduled_works+0x8e0/0x1770 kernel/workqueue.c:3335 #1: ffffc90003b6fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3230 [inline] #1: ffffc90003b6fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_scheduled_works+0x91b/0x1770 kernel/workqueue.c:3335 #2: ffff8880665d0078 (&hdev->lock){+.+.}-{3:3}, at: hci_le_create_big_complete_evt+0xcf/0xae0 net/bluetooth/hci_event.c:6914 #3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline] #3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline] #3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: hci_le_create_big_complete_evt+0xdb/0xae0 net/bluetooth/hci_event.c:6915 CPU: 0 PID: 5070 Comm: kworker/u9:2 Not tainted 6.8.0-syzkaller-08073-g480e035fc4c7 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 Workqueue: hci0 hci_rx_work Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 __might_resched+0x5d4/0x780 kernel/sched/core.c:10187 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0xc1/0xd70 kernel/locking/mutex.c:752 hci_connect_cfm include/net/bluetooth/hci_core.h:2004 [inline] hci_le_create_big_complete_evt+0x3d9/0xae0 net/bluetooth/hci_event.c:6939 hci_event_func net/bluetooth/hci_event.c:7514 [inline] hci_event_packet+0xa53/0x1540 net/bluetooth/hci_event.c:7569 hci_rx_work+0x3e8/0xca0 net/bluetooth/hci_core.c:4171 process_one_work kernel/workqueue.c:3254 [inline] process_scheduled_works+0xa00/0x1770 kernel/workqueue.c:3335 worker_thread+0x86d/0xd70 kernel/workqueue.c:3416 kthread+0x2f0/0x390 kernel/kthread.c:388 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243 Reported-by: syzbot+2fb0835e0c9cefc34614@syzkaller.appspotmail.com Tested-by: syzbot+2fb0835e0c9cefc34614@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=2fb0835e0c9cefc34614 Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin