kernel/git/next/linux-next.git/net/bluetooth/l2cap_sock.c, branch master

Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_new_connection_cb()

2026-06-29T19:12:25+00:00

l2cap_sock_new_connection_cb() returned l2cap_pi(sk)->chan after release_sock(parent). Once the parent lock is dropped the newly enqueued child socket sk is reachable via the accept queue, so another task can accept and free it before the callback dereferences sk, resulting in a use-after-free. Rework the ->new_connection() op so the core, rather than the callback, owns the child channel's lifetime. The op now receives a pre-allocated new_chan and returns an errno instead of allocating and returning a channel. l2cap_new_connection() allocates the child channel and links it into the conn list via __l2cap_chan_add() before invoking the callback, so the conn-list reference keeps the channel alive once release_sock(parent) exposes the socket to other tasks. Channel configuration that was duplicated in l2cap_sock_init() and the various new_connection callbacks is consolidated into l2cap_chan_set_defaults(), which now inherits from the parent channel when one is supplied. Fixes: 8ffb929098a5 ("Bluetooth: Remove parent socket usage from l2cap_core.c") Cc: stable@kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Siwei Zhang Signed-off-by: Luiz Augusto von Dentz

Bluetooth: fix UAF in bt_accept_dequeue()

2026-06-29T18:05:53+00:00

bt_accept_get() takes a temporary reference before dropping the accept queue lock. bt_accept_dequeue() currently drops that reference before bt_accept_unlink(), leaving only the queue reference. bt_accept_unlink() drops the queue reference. The subsequent sock_hold() therefore accesses freed memory if it was the final reference, as observed by KASAN during listening L2CAP socket cleanup. Retain the temporary queue-walk reference through unlink and hand it to the caller on success. Drop it explicitly on the closed and not-yet-connected paths. Fixes: ab1513597c6c ("Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del()") Reported-by: syzbot+674ff7e4d7fdfd572afc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=674ff7e4d7fdfd572afc Cc: stable@vger.kernel.org Signed-off-by: Yousef Alhouseen Signed-off-by: Luiz Augusto von Dentz

Bluetooth: L2CAP: Add minimal context analysis annotations

2026-06-15T21:51:33+00:00

Add minimal compiler context analysis annotations, required for compilation to pass. Don't check complex conn->lock usage in l2cap_sock_shutdown(). The analysis cannot know that chan->conn pointer is never replaced by a different l2cap_conn. Signed-off-by: Pauli Virtanen Signed-off-by: Luiz Augusto von Dentz

Bluetooth: Add SPDX id lines to some source files

2026-06-11T18:24:41+00:00

Many bluetooth source files are missing SPDX-License-Identifier lines. Add appropriate IDs to these files, and remove other license lines from the headers. Leave the warranty disclaimer in files where the license ID is GPL-2.0 but the wording of the disclaimer is slightly different from that of the GPL v2 disclaimer. It is not different enough to cause licensing conflicts, but is kept to honor the original contributors' legal intent. Signed-off-by: Tim Bird Signed-off-by: Luiz Augusto von Dentz

Bluetooth: L2CAP: convert to getsockopt_iter

2026-06-11T18:24:39+00:00

Convert L2CAP socket's getsockopt implementation to use the new getsockopt_iter callback with sockopt_t. Key changes: - Replace (char __user *optval, int __user *optlen) with sockopt_t *sopt - Use sopt->optlen for buffer length (input) - Use copy_to_iter() instead of put_user()/copy_to_user() - Add linux/uio.h for copy_to_iter() The sockopt_t parameter is named sopt rather than opt to avoid collision with the existing local u32 opt used by L2CAP_LM. The same naming is reused for the new u32 helper in l2cap_sock_getsockopt(), with mtu and mval helpers covering the u16 and u8 cases. Signed-off-by: Breno Leitao Signed-off-by: Luiz Augusto von Dentz

Bluetooth: L2CAP: use chan timer to close channels in cleanup_listen()

2026-05-27T20:44:01+00:00

l2cap_chan_close() removes the channel from conn->chan_l, which must be done under conn->lock. cleanup_listen() runs under the parent sk_lock, so acquiring conn->lock would invert the established conn->lock -> chan->lock -> sk_lock order. Instead of calling l2cap_chan_close() directly, schedule l2cap_chan_timeout with delay 0 to close the channel asynchronously. The timeout handler already acquires conn->lock and chan->lock in the correct order. The timer is only armed when chan->conn is still set: if it is already NULL, l2cap_conn_del() has already processed this channel (l2cap_chan_del + l2cap_sock_teardown_cb + l2cap_sock_close_cb), so there is nothing left to do. If l2cap_conn_del() races in after the timer is armed, __clear_chan_timer() inside l2cap_chan_del() cancels it; if the timer has already fired, the handler returns harmlessly because chan->conn was cleared. Fixes: 3df91ea20e74 ("Bluetooth: Revert to mutexes from RCU list") Cc: # 0b58004: Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del() Signed-off-by: Siwei Zhang Signed-off-by: Luiz Augusto von Dentz

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

2026-05-20T20:35:47+00:00

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

Bluetooth: L2CAP: Fix null-ptr-deref in l2cap_sock_new_connection_cb()

2026-05-06T20:21:09+00:00

Add the same NULL guard already present in l2cap_sock_resume_cb() and l2cap_sock_ready_cb(). Fixes: 80808e431e1e ("Bluetooth: Add l2cap_chan_ops abstraction") Cc: stable@kernel.org Signed-off-by: Siwei Zhang Signed-off-by: Luiz Augusto von Dentz

Bluetooth: L2CAP: Fix null-ptr-deref in l2cap_sock_get_sndtimeo_cb()

2026-05-06T20:21:07+00:00

Add the same NULL guard already present in l2cap_sock_resume_cb() and l2cap_sock_ready_cb(). Fixes: 8d836d71e222 ("Bluetooth: Access sk_sndtimeo indirectly in l2cap_core.c") Cc: stable@kernel.org Signed-off-by: Siwei Zhang Signed-off-by: Luiz Augusto von Dentz

Bluetooth: L2CAP: Fix null-ptr-deref in l2cap_sock_state_change_cb()

2026-05-06T20:21:04+00:00

Add the same NULL guard already present in l2cap_sock_resume_cb() and l2cap_sock_ready_cb(). Fixes: 89bc500e41fc ("Bluetooth: Add state tracking to struct l2cap_chan") Cc: stable@kernel.org Signed-off-by: Siwei Zhang Signed-off-by: Luiz Augusto von Dentz