* [PATCH v2 1/2] Bluetooth: ISO: Fix data-race on dst in iso_sock_connect()
2026-04-21 2:51 [PATCH v2 0/2] Bluetooth: ISO: Fix KCSAN data-races on iso_pi(sk) SeungJu Cheon
@ 2026-04-21 2:51 ` SeungJu Cheon
2026-04-21 2:51 ` [PATCH v2 2/2] Bluetooth: ISO: Fix data-race on iso_pi(sk) in socket and HCI event paths SeungJu Cheon
1 sibling, 0 replies; 3+ messages in thread
From: SeungJu Cheon @ 2026-04-21 2:51 UTC (permalink / raw)
To: luiz.dentz, marcel
Cc: linux-bluetooth, netdev, linux-kernel, me, skhan,
linux-kernel-mentees, SeungJu Cheon
iso_sock_connect() copies the destination address into
iso_pi(sk)->dst under lock_sock, then releases the lock and reads
it back with bacmp() to decide between the CIS and BIS connect
paths:
lock_sock(sk);
bacpy(&iso_pi(sk)->dst, &sa->iso_bdaddr);
iso_pi(sk)->dst_type = sa->iso_bdaddr_type;
release_sock(sk);
if (bacmp(&iso_pi(sk)->dst, BDADDR_ANY)) // <- no lock held
This read after release_sock() races with any concurrent write to
iso_pi(sk)->dst on the same socket.
Fix by reading the destination address directly from the local
sockaddr argument (sa->iso_bdaddr) instead of iso_pi(sk)->dst.
Since sa is a function-local argument, reading it requires no
locking and avoids the race.
This patch addresses only the bacmp() race in iso_sock_connect();
other unprotected iso_pi(sk) accesses are fixed separately in the
next patch.
KCSAN report:
BUG: KCSAN: data-race in memcmp+0x39/0xb0
race at unknown origin, with read to 0xffff8f96ea66dde3 of 1 bytes by task 549 on cpu 1:
memcmp+0x39/0xb0
iso_sock_connect+0x275/0xb40
__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
value changed: 0x00 -> 0xee
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 549 Comm: iso_race_combin Not tainted 7.0.0-08391-g1d51b370a0f8 #40 PREEMPT(lazy)
Fixes: ccf74f2390d6 ("Bluetooth: Add BTPROTO_ISO socket type")
Signed-off-by: SeungJu Cheon <suunj1331@gmail.com>
---
net/bluetooth/iso.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index be145e2736b7..290a1b9a9daa 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -1193,7 +1193,7 @@ static int iso_sock_connect(struct socket *sock, struct sockaddr_unsized *addr,
release_sock(sk);
- if (bacmp(&iso_pi(sk)->dst, BDADDR_ANY))
+ if (bacmp(&sa->iso_bdaddr, BDADDR_ANY))
err = iso_connect_cis(sk);
else
err = iso_connect_bis(sk);
--
2.52.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH v2 2/2] Bluetooth: ISO: Fix data-race on iso_pi(sk) in socket and HCI event paths
2026-04-21 2:51 [PATCH v2 0/2] Bluetooth: ISO: Fix KCSAN data-races on iso_pi(sk) SeungJu Cheon
2026-04-21 2:51 ` [PATCH v2 1/2] Bluetooth: ISO: Fix data-race on dst in iso_sock_connect() SeungJu Cheon
@ 2026-04-21 2:51 ` SeungJu Cheon
1 sibling, 0 replies; 3+ messages in thread
From: SeungJu Cheon @ 2026-04-21 2:51 UTC (permalink / raw)
To: luiz.dentz, marcel
Cc: linux-bluetooth, netdev, linux-kernel, me, skhan,
linux-kernel-mentees, SeungJu Cheon
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 <suunj1331@gmail.com>
---
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
^ permalink raw reply related [flat|nested] 3+ messages in thread