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Tue, 09 Jun 2026 23:09:53 -0700 (PDT) Received: from secrnd-cstp.tailb7f510.ts.net ([125.131.91.97]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-37625ecfed4sm787508a91.0.2026.06.09.23.09.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jun 2026 23:09:52 -0700 (PDT) From: Sanghyun Park To: marcel@holtmann.org, johan.hedberg@gmail.com, luiz.dentz@gmail.com Cc: Sanghyun Park , linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] Bluetooth: SCO: Fix use-after-free on listening socket in sco_conn_ready() Date: Wed, 10 Jun 2026 15:08:24 +0900 Message-ID: <20260610060824.552957-2-sanghyun.park.cnu@gmail.com> X-Mailer: git-send-email 2.48.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" sco_conn_ready() calls sco_get_sock_listen() which returns a raw pointer to a listening socket without taking a reference. After releasing sco_sk_list.lock, a concurrent close() of the listening socket can free it between the list lookup return and lock_sock(parent), resulting in a use-after-free. Fix by taking a reference with sock_hold() inside sco_get_sock_listen() while the list lock is still held, and dropping it with sock_put() in sco_conn_ready() after release_sock(). Race: CPU0 (HCI event workqueue) CPU1 (userspace) =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D sco_conn_ready(): parent =3D sco_get_sock_listen() // returns parent without a reference close(listen_fd): sco_sock_release() sco_sock_kill() sock_put(parent) -> frees parent lock_sock(parent) // UAF: parent may already be freed Signed-off-by: Sanghyun Park --- Changes in v2: - Move sock_hold() from sco_conn_ready() into sco_get_sock_listen() so the reference is taken while sco_sk_list.lock is still held. - Drop the verbose reproduction/KASAN text, personal note, and unverified Fixes tag from the commit message. - Fix whitespace damage. net/bluetooth/sco.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c index 6383db54657..20518bbc93a 100644 --- a/net/bluetooth/sco.c +++ b/net/bluetooth/sco.c @@ -410,6 +410,11 @@ static struct sock *sco_get_sock_listen(bdaddr_t *src) sk1 =3D sk; } =20 + if (sk) + sock_hold(sk); + else if (sk1) + sock_hold(sk1); + read_unlock(&sco_sk_list.lock); =20 return sk ? sk : sk1; @@ -1336,6 +1341,7 @@ static void sco_conn_ready(struct sco_conn *conn) BTPROTO_SCO, GFP_ATOMIC, 0); if (!sk) { release_sock(parent); + sock_put(parent); sco_conn_unlock(conn); return; } @@ -1357,6 +1363,7 @@ static void sco_conn_ready(struct sco_conn *conn) parent->sk_data_ready(parent); =20 release_sock(parent); + sock_put(parent); =20 sco_conn_unlock(conn); }