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Bluetooth: ISO: avoid NULL deref of conn in iso_conn_big_sync()

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iso_conn_big_sync() drops the socket lock to call hci_get_route() and
then re-acquires it, but dereferences iso_pi(sk)->conn->hcon afterwards
without re-checking that conn is still valid.

While the lock is dropped, the connection can be torn down under the
same socket lock: iso_disconn_cfm() -> iso_conn_del() -> iso_chan_del()
sets iso_pi(sk)->conn to NULL (and the broadcast teardown path can also
clear conn->hcon on its own). When iso_conn_big_sync() re-acquires the
lock and reads conn->hcon, conn may be NULL, causing a NULL pointer
dereference (hcon is the first member of struct iso_conn).

This path is reached from iso_sock_recvmsg() for a PA-sync broadcast
sink socket (BT_SK_DEFER_SETUP | BT_SK_PA_SYNC), so the dropped-lock
window can race with connection teardown driven by controller events.

Re-validate iso_pi(sk)->conn and its hcon after re-acquiring the socket
lock and bail out if the connection went away, as already done in the
sibling iso_sock_rebind_bc().

Fixes: 7a17308c17 ("Bluetooth: iso: Fix circular lock in iso_conn_big_sync")
Cc: stable@vger.kernel.org
Signed-off-by: Muhammad Bilal <meatuni001@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
This commit is contained in:
Muhammad Bilal 2026-06-21 21:23:05 +05:00 committed by Luiz Augusto von Dentz
parent fa85d985f6
commit d5541eb148
1 changed files with 12 additions and 1 deletions
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13
net/bluetooth/iso.c
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@ -1590,6 +1590,7 @@ static void iso_conn_big_sync(struct sock *sk)
{
int err;
struct hci_dev *hdev;
struct iso_conn *conn;
bdaddr_t src, dst;
u8 src_type;
@ -1612,8 +1613,17 @@ static void iso_conn_big_sync(struct sock *sk)
hci_dev_lock(hdev);
lock_sock(sk);
/* The socket lock was dropped for hci_get_route(), so the connection
* may have been torn down meanwhile: iso_chan_del() clears conn and
* the broadcast teardown path can clear conn->hcon on its own. Check
* both before dereferencing conn->hcon.
*/
conn = iso_pi(sk)->conn;
if (!conn || !conn->hcon)
goto unlock;
if (!test_and_set_bit(BT_SK_BIG_SYNC, &iso_pi(sk)->flags)) {
err = hci_conn_big_create_sync(hdev, iso_pi(sk)->conn->hcon,
err = hci_conn_big_create_sync(hdev, conn->hcon,
&iso_pi(sk)->qos,
iso_pi(sk)->sync_handle,
iso_pi(sk)->bc_num_bis,
@ -1622,6 +1632,7 @@ static void iso_conn_big_sync(struct sock *sk)
bt_dev_err(hdev, "hci_big_create_sync: %d", err);
}
unlock:
release_sock(sk);
hci_dev_unlock(hdev);
hci_dev_put(hdev);