From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5197B4F798D; Tue, 13 Oct 2026 12:19:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791893955; cv=none; b=Kax8y3CgaDYPDnXm9qqopd3TSHLc6rokzycLLmn3UDXNQ53K1mC18fsvNImJPmaueBapGYTm93qM1GjeDNPWOOHAW+GaCzWTJoea+zGqNCu8gz3b4gkcp4BaQVQ6AmDyUez6t/+6PMkwADW898140lCHexaIClbiqGr5/p5F8/0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791893955; c=relaxed/simple; bh=YtyCousPaUPmrXZO+cMLlSBpkPgGJOgV+lefc86QBqY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MZ1uS5oLBN1gR1osbEx8/a8ZDT1hYJd2dqDhvyIAf6DPPsQzqaXcBKLrYi9XVewTa1A4p56jOixRUdqh1aN1BHKrr7/7pNVPuTdxjRp9LWEqriw402ZcqmK3d09EslSFmjmFZBCMWSQ1rKf+cSy2Au0Is/f5FkDbOWLyrLp3y34= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Dj3DdsQy; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Dj3DdsQy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46C4E1F000FF; Tue, 13 Oct 2026 12:19:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791893953; bh=L1MWsbhXSNNwZ+EBkl3j2Zi9h8gxlNWngh21sqydays=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Dj3DdsQy9HGAPhUxMh1BlMYQuToQOHOBWqHBQun3QjyI0hhGAGVS+W4Z07rjN5a8y 1tUTlKTl2EcmR5JD3JQPrRzZ5kjxS9y6gOK9KKNNhpl9CzOMTDmovxl0/yYhxsLb9K 1BnoZCuHmiEodAT1KTpu7zxoPTrs9E86zw42PT38= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+b106284c2a0b7bc80cf9@syzkaller.appspotmail.com, Pauli Virtanen , Luiz Augusto von Dentz , Sasha Levin Subject: [PATCH 6.18 399/621] Bluetooth: L2CAP: access chan->conn safely in get/setsockopt Date: Tue, 13 Oct 2026 13:36:34 +0200 Message-ID: <20261013112930.310444024@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261013112920.855194808@linuxfoundation.org> References: <20261013112920.855194808@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pauli Virtanen [ Upstream commit ca2c4c26498643f421d35ffe258fafbd3ed461c3 ] Since commit b66774b48dd9 ("Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref") l2cap_chan::conn has held reference and remains non-NULL also after the corresponding hci_conn is deleted. In this state accessing various fields eg. hci_conn::hdev is invalid, which leads to KASAN crash in l2cap_sock_setsockopt() access of conn->hcon->hdev. Check l2cap_chan::conn.hcon corresponds to an alive hci_conn before trying to use it in l2cap_sock.c. Hold l2cap_chan_lock() in getsockopt/setsockopt to ensure it stays alive, and to avoid data races in l2cap_chan fields. Fixes: b66774b48dd9 ("Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref") Reported-by: syzbot+b106284c2a0b7bc80cf9@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=b106284c2a0b7bc80cf9 Signed-off-by: Pauli Virtanen Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin --- net/bluetooth/l2cap_sock.c | 57 ++++++++++++++++++++++++++++++-------- 1 file changed, 46 insertions(+), 11 deletions(-) diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index 496482141e892..9078a672e2dd3 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -438,11 +438,26 @@ static int l2cap_get_mode(struct l2cap_chan *chan) return -EINVAL; } +static struct l2cap_conn *l2cap_chan_conn(struct l2cap_chan *chan) +{ + lockdep_assert_held(&chan->lock); + + /* l2cap_conn_del() sets FLAG_DEL while holding chan->lock before + * conn->hcon is deleted. If not set and conn is non-NULL, conn->hcon + * remains alive during this chan->lock critical section. + */ + if (test_bit(FLAG_DEL, &chan->flags)) + return NULL; + + return chan->conn; +} + static int l2cap_sock_getsockopt_old(struct socket *sock, int optname, char __user *optval, int __user *optlen) { struct sock *sk = sock->sk; struct l2cap_chan *chan = l2cap_pi(sk)->chan; + struct l2cap_conn *conn; struct l2cap_options opts; struct l2cap_conninfo cinfo; int err = 0; @@ -454,6 +469,7 @@ static int l2cap_sock_getsockopt_old(struct socket *sock, int optname, if (get_user(len, optlen)) return -EFAULT; + l2cap_chan_lock(chan); lock_sock(sk); switch (optname) { @@ -539,9 +555,15 @@ static int l2cap_sock_getsockopt_old(struct socket *sock, int optname, break; } + conn = l2cap_chan_conn(chan); + if (!conn) { + err = -ENOTCONN; + break; + } + memset(&cinfo, 0, sizeof(cinfo)); - cinfo.hci_handle = chan->conn->hcon->handle; - memcpy(cinfo.dev_class, chan->conn->hcon->dev_class, 3); + cinfo.hci_handle = conn->hcon->handle; + memcpy(cinfo.dev_class, conn->hcon->dev_class, 3); len = min(len, sizeof(cinfo)); if (copy_to_user(optval, (char *) &cinfo, len)) @@ -555,6 +577,8 @@ static int l2cap_sock_getsockopt_old(struct socket *sock, int optname, } release_sock(sk); + l2cap_chan_unlock(chan); + return err; } @@ -563,6 +587,7 @@ static int l2cap_sock_getsockopt(struct socket *sock, int level, int optname, { struct sock *sk = sock->sk; struct l2cap_chan *chan = l2cap_pi(sk)->chan; + struct l2cap_conn *conn; struct bt_security sec; struct bt_power pwr; u32 phys; @@ -579,6 +604,7 @@ static int l2cap_sock_getsockopt(struct socket *sock, int level, int optname, if (get_user(len, optlen)) return -EFAULT; + l2cap_chan_lock(chan); lock_sock(sk); switch (optname) { @@ -590,12 +616,14 @@ static int l2cap_sock_getsockopt(struct socket *sock, int level, int optname, break; } + conn = l2cap_chan_conn(chan); + memset(&sec, 0, sizeof(sec)); - if (chan->conn) { - sec.level = chan->conn->hcon->sec_level; + if (conn) { + sec.level = conn->hcon->sec_level; if (sk->sk_state == BT_CONNECTED) - sec.key_size = chan->conn->hcon->enc_key_size; + sec.key_size = conn->hcon->enc_key_size; } else { sec.level = chan->sec_level; } @@ -671,12 +699,14 @@ static int l2cap_sock_getsockopt(struct socket *sock, int level, int optname, break; case BT_PHY: - if (sk->sk_state != BT_CONNECTED) { + conn = l2cap_chan_conn(chan); + + if (sk->sk_state != BT_CONNECTED || !conn) { err = -ENOTCONN; break; } - phys = hci_conn_get_phy(chan->conn->hcon); + phys = hci_conn_get_phy(conn->hcon); if (put_user(phys, (u32 __user *) optval)) err = -EFAULT; @@ -709,6 +739,7 @@ static int l2cap_sock_getsockopt(struct socket *sock, int level, int optname, } release_sock(sk); + l2cap_chan_unlock(chan); return err; } @@ -739,6 +770,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, BT_DBG("sk %p", sk); + l2cap_chan_lock(chan); lock_sock(sk); switch (optname) { @@ -840,6 +872,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, } release_sock(sk); + l2cap_chan_unlock(chan); return err; } @@ -903,6 +936,7 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname, if (level != SOL_BLUETOOTH) return -ENOPROTOOPT; + l2cap_chan_lock(chan); lock_sock(sk); switch (optname) { @@ -928,11 +962,10 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname, chan->sec_level = sec.level; - if (!chan->conn) + conn = l2cap_chan_conn(chan); + if (!conn) break; - conn = chan->conn; - /* change security for LE channels */ if (chan->scid == L2CAP_CID_ATT) { if (smp_conn_security(conn->hcon, sec.level)) { @@ -987,7 +1020,8 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname, } if (opt == BT_FLUSHABLE_OFF) { - conn = chan->conn; + conn = l2cap_chan_conn(chan); + /* proceed further only when we have l2cap_conn and No Flush support in the LM */ if (!conn || !lmp_no_flush_capable(conn->hcon->hdev)) { @@ -1111,6 +1145,7 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname, } release_sock(sk); + l2cap_chan_unlock(chan); return err; } -- 2.53.0