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Mon, 20 Apr 2026 19:51:35 -0700 (PDT) From: SeungJu Cheon To: luiz.dentz@gmail.com, marcel@holtmann.org Cc: linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, me@brighamcampbell.com, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linux.dev, SeungJu Cheon Subject: [PATCH v2 2/2] Bluetooth: ISO: Fix data-race on iso_pi(sk) in socket and HCI event paths Date: Tue, 21 Apr 2026 11:51:22 +0900 Message-ID: <20260421025122.55781-3-suunj1331@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260421025122.55781-1-suunj1331@gmail.com> References: <20260421025122.55781-1-suunj1331@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Several iso_pi(sk) fields (qos, qos_user_set, bc_sid, base, base_len, sync_handle, bc_num_bis) are written under lock_sock in iso_sock_setsockopt() and iso_sock_bind(), but read and written under hci_dev_lock only in two other paths: - iso_connect_bis() / iso_connect_cis(), invoked from connect(2), read qos/base/bc_sid and reset qos to default_qos on the qos_user_set validation failure -- all without lock_sock. - iso_connect_ind(), invoked from hci_rx_work, writes sync_handle, bc_sid, qos.bcast.encryption, bc_num_bis, base and base_len on PA_SYNC_ESTABLISHED / PAST_RECEIVED / BIG_INFO_ADV_REPORT / PER_ADV_REPORT events. The BIG_INFO handler additionally passes &iso_pi(sk)->qos together with sync_handle / bc_num_bis / bc_bis to hci_conn_big_create_sync() while setsockopt may be mutating them. Acquire lock_sock around the affected accesses in both paths. The locking order hci_dev_lock -> lock_sock matches the existing iso_conn_big_sync() precedent, whose comment documents the same requirement for hci_conn_big_create_sync(). The HCI connect/bind helpers do not wait for command completion -- they enqueue work via hci_cmd_sync_queue{,_once}() / hci_le_create_cis_pending() and return -- so the added hold time is comparable to iso_conn_big_sync(). KCSAN report: BUG: KCSAN: data-race in iso_connect_cis / iso_sock_setsockopt read to 0xffffa3ae8ce3cdc8 of 1 bytes by task 335 on cpu 0: iso_connect_cis+0x49f/0xa20 iso_sock_connect+0x60e/0xb40 __sys_connect_file+0xbd/0xe0 __sys_connect+0xe0/0x110 __x64_sys_connect+0x40/0x50 x64_sys_call+0xcad/0x1c60 do_syscall_64+0x133/0x590 entry_SYSCALL_64_after_hwframe+0x77/0x7f write to 0xffffa3ae8ce3cdc8 of 60 bytes by task 334 on cpu 1: iso_sock_setsockopt+0x69a/0x930 do_sock_setsockopt+0xc3/0x170 __sys_setsockopt+0xd1/0x130 __x64_sys_setsockopt+0x64/0x80 x64_sys_call+0x1547/0x1c60 do_syscall_64+0x133/0x590 entry_SYSCALL_64_after_hwframe+0x77/0x7f Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 334 Comm: iso_setup_race Not tainted 7.0.0-10949-g8541d8f725c6 #44 PREEMPT(lazy) The iso_connect_ind() races were found by inspection. Fixes: ccf74f2390d6 ("Bluetooth: Add BTPROTO_ISO socket type") Signed-off-by: SeungJu Cheon --- net/bluetooth/iso.c | 54 +++++++++++++++++++++++++-------------------- 1 file changed, 30 insertions(+), 24 deletions(-) diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c index 290a1b9a9daa..7cb2864fe872 100644 --- a/net/bluetooth/iso.c +++ b/net/bluetooth/iso.c @@ -347,6 +347,7 @@ static int iso_connect_bis(struct sock *sk) return -EHOSTUNREACH; hci_dev_lock(hdev); + lock_sock(sk); if (!bis_capable(hdev)) { err = -EOPNOTSUPP; @@ -399,13 +400,9 @@ static int iso_connect_bis(struct sock *sk) goto unlock; } - lock_sock(sk); - err = iso_chan_add(conn, sk, NULL); - if (err) { - release_sock(sk); + if (err) goto unlock; - } /* Update source addr of the socket */ bacpy(&iso_pi(sk)->src, &hcon->src); @@ -421,9 +418,8 @@ static int iso_connect_bis(struct sock *sk) iso_sock_set_timer(sk, READ_ONCE(sk->sk_sndtimeo)); } - release_sock(sk); - unlock: + release_sock(sk); hci_dev_unlock(hdev); hci_dev_put(hdev); return err; @@ -444,6 +440,7 @@ static int iso_connect_cis(struct sock *sk) return -EHOSTUNREACH; hci_dev_lock(hdev); + lock_sock(sk); if (!cis_central_capable(hdev)) { err = -EOPNOTSUPP; @@ -498,13 +495,9 @@ static int iso_connect_cis(struct sock *sk) goto unlock; } - lock_sock(sk); - err = iso_chan_add(conn, sk, NULL); - if (err) { - release_sock(sk); + if (err) goto unlock; - } /* Update source addr of the socket */ bacpy(&iso_pi(sk)->src, &hcon->src); @@ -520,9 +513,8 @@ static int iso_connect_cis(struct sock *sk) iso_sock_set_timer(sk, READ_ONCE(sk->sk_sndtimeo)); } - release_sock(sk); - unlock: + release_sock(sk); hci_dev_unlock(hdev); hci_dev_put(hdev); return err; @@ -2256,8 +2248,10 @@ int iso_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags) sk = iso_get_sock(hdev, &hdev->bdaddr, bdaddr, BT_LISTEN, iso_match_sid, ev1); if (sk && !ev1->status) { + lock_sock(sk); iso_pi(sk)->sync_handle = le16_to_cpu(ev1->handle); iso_pi(sk)->bc_sid = ev1->sid; + release_sock(sk); } goto done; @@ -2268,8 +2262,10 @@ int iso_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags) sk = iso_get_sock(hdev, &hdev->bdaddr, bdaddr, BT_LISTEN, iso_match_sid_past, ev1a); if (sk && !ev1a->status) { + lock_sock(sk); iso_pi(sk)->sync_handle = le16_to_cpu(ev1a->sync_handle); iso_pi(sk)->bc_sid = ev1a->sid; + release_sock(sk); } goto done; @@ -2296,27 +2292,35 @@ int iso_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags) ev2); if (sk) { - int err; - struct hci_conn *hcon = iso_pi(sk)->conn->hcon; + int err = 0; + bool big_sync; + struct hci_conn *hcon; + lock_sock(sk); + + hcon = iso_pi(sk)->conn->hcon; iso_pi(sk)->qos.bcast.encryption = ev2->encryption; if (ev2->num_bis < iso_pi(sk)->bc_num_bis) iso_pi(sk)->bc_num_bis = ev2->num_bis; - if (!test_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags) && - !test_and_set_bit(BT_SK_BIG_SYNC, &iso_pi(sk)->flags)) { + big_sync = !test_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags) && + !test_and_set_bit(BT_SK_BIG_SYNC, &iso_pi(sk)->flags); + + if (big_sync) err = hci_conn_big_create_sync(hdev, hcon, &iso_pi(sk)->qos, iso_pi(sk)->sync_handle, iso_pi(sk)->bc_num_bis, iso_pi(sk)->bc_bis); - if (err) { - bt_dev_err(hdev, "hci_le_big_create_sync: %d", - err); - sock_put(sk); - sk = NULL; - } + + release_sock(sk); + + if (big_sync && err) { + bt_dev_err(hdev, "hci_le_big_create_sync: %d", + err); + sock_put(sk); + sk = NULL; } } @@ -2370,8 +2374,10 @@ int iso_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags) if (!base || base_len > BASE_MAX_LENGTH) goto done; + lock_sock(sk); memcpy(iso_pi(sk)->base, base, base_len); iso_pi(sk)->base_len = base_len; + release_sock(sk); } else { /* This is a PA data fragment. Keep pa_data_len set to 0 * until all data has been reassembled. -- 2.52.0