From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 09D6721D00A; Mon, 23 Mar 2026 14:09:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774274956; cv=none; b=EkeUS1G9bWsTASHm/PyMDjDomLE9vYCrSfsuuityCnpxbHgovsAGW/eT7nDxaMHKQuy9XqgpS1K1DvFWab+dn73NgR7zNKimSrJPEoJYGjFSb0eHf/UPtMGsClaAektRq59dbmKSTP1hc6BP6EkwuzT6v1CwE6R0pfEQXOC42W8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774274956; c=relaxed/simple; bh=QZmiPlYcKQOCP4J8kRXxWg1O9enlnKGTMmQ1WklChBU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Iw2Qr3GxIfdHnazYAuSzUVyDJro4PYi1M2fG3dvNkYrIPin/mZhK5bcQS6GYlUncVam9xCxAJMUalOPSpgpYKbjj0p9sflQNnk45BhKPTYPVI1fNSss1aejfvoX517IxQfIMJPjmb4q12IQjRSxXmzr2F+zk6am+bYFi9fWjq2E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=jJWqLxX7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="jJWqLxX7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 926AAC4CEF7; Mon, 23 Mar 2026 14:09:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774274955; bh=QZmiPlYcKQOCP4J8kRXxWg1O9enlnKGTMmQ1WklChBU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jJWqLxX7aNN6RaQBpIkTzebB1hCm3WOJkgkrP2CFRnX5ZqChoxAJo+8HCK87is4TY wXXANOfxJz11vAa33Ws88WOawGhiIiMoJRO85aZhvCsRyNdk3aI7FIr4e8K64zfZsb MQGjEvsJJW+u/kVSZM5J5kAWGrorHFEUYedjiTkk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+14b6d57fb728e27ce23c@syzkaller.appspotmail.com, Shaurya Rane , Luiz Augusto von Dentz , Sasha Levin Subject: [PATCH 6.18 129/212] Bluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user Date: Mon, 23 Mar 2026 14:45:50 +0100 Message-ID: <20260323134507.846374370@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323134503.770111826@linuxfoundation.org> References: <20260323134503.770111826@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org 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: Shaurya Rane [ Upstream commit 752a6c9596dd25efd6978a73ff21f3b592668f4a ] After commit ab4eedb790ca ("Bluetooth: L2CAP: Fix corrupted list in hci_chan_del"), l2cap_conn_del() uses conn->lock to protect access to conn->users. However, l2cap_register_user() and l2cap_unregister_user() don't use conn->lock, creating a race condition where these functions can access conn->users and conn->hchan concurrently with l2cap_conn_del(). This can lead to use-after-free and list corruption bugs, as reported by syzbot. Fix this by changing l2cap_register_user() and l2cap_unregister_user() to use conn->lock instead of hci_dev_lock(), ensuring consistent locking for the l2cap_conn structure. Reported-by: syzbot+14b6d57fb728e27ce23c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=14b6d57fb728e27ce23c Fixes: ab4eedb790ca ("Bluetooth: L2CAP: Fix corrupted list in hci_chan_del") Signed-off-by: Shaurya Rane Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin --- net/bluetooth/l2cap_core.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index 05acc2e98f58f..9ea030fc9a9cc 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -1686,17 +1686,15 @@ static void l2cap_info_timeout(struct work_struct *work) int l2cap_register_user(struct l2cap_conn *conn, struct l2cap_user *user) { - struct hci_dev *hdev = conn->hcon->hdev; int ret; /* We need to check whether l2cap_conn is registered. If it is not, we - * must not register the l2cap_user. l2cap_conn_del() is unregisters - * l2cap_conn objects, but doesn't provide its own locking. Instead, it - * relies on the parent hci_conn object to be locked. This itself relies - * on the hci_dev object to be locked. So we must lock the hci device - * here, too. */ + * must not register the l2cap_user. l2cap_conn_del() unregisters + * l2cap_conn objects under conn->lock, and we use the same lock here + * to protect access to conn->users and conn->hchan. + */ - hci_dev_lock(hdev); + mutex_lock(&conn->lock); if (!list_empty(&user->list)) { ret = -EINVAL; @@ -1717,16 +1715,14 @@ int l2cap_register_user(struct l2cap_conn *conn, struct l2cap_user *user) ret = 0; out_unlock: - hci_dev_unlock(hdev); + mutex_unlock(&conn->lock); return ret; } EXPORT_SYMBOL(l2cap_register_user); void l2cap_unregister_user(struct l2cap_conn *conn, struct l2cap_user *user) { - struct hci_dev *hdev = conn->hcon->hdev; - - hci_dev_lock(hdev); + mutex_lock(&conn->lock); if (list_empty(&user->list)) goto out_unlock; @@ -1735,7 +1731,7 @@ void l2cap_unregister_user(struct l2cap_conn *conn, struct l2cap_user *user) user->remove(conn, user); out_unlock: - hci_dev_unlock(hdev); + mutex_unlock(&conn->lock); } EXPORT_SYMBOL(l2cap_unregister_user); -- 2.51.0