From patchwork Sun Apr 30 18:05:35 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ruihan Li X-Patchwork-Id: 13227261 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 90EF9C77B60 for ; Sun, 30 Apr 2023 18:05:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230211AbjD3SFz (ORCPT ); Sun, 30 Apr 2023 14:05:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229568AbjD3SFz (ORCPT ); Sun, 30 Apr 2023 14:05:55 -0400 Received: from pku.edu.cn (mx19.pku.edu.cn [162.105.129.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B5ED8E7B for ; Sun, 30 Apr 2023 11:05:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pku.edu.cn; s=dkim; h=Received:From:To:Cc:Subject:Date: Message-Id:MIME-Version:Content-Transfer-Encoding; bh=SG+O2Nuecm o3S1C5gW1OXRfwUABkZXk/+etEKv1A1Wo=; b=lJYPCkdSBpS0jLLYMHxp8CsLto yh77CSpQXJ5JUSnNA2fqBJnrPgJ+wP/lPYybxwet8TQrXPOroglJS44jhNIJF+Gu iDYeJbEiMATbzRJLQpUv3HEiLOzaQKfKsLuSSRAxP4OMmKK+eeduSZIIHxjWCO4Q bc5PQLxdOtckID/XU= Received: from localhost.localdomain (unknown [10.7.101.92]) by front01 (Coremail) with SMTP id 5oFpogBXX2f2rU5kiWv2AA--.57652S2; Mon, 01 May 2023 02:05:47 +0800 (CST) From: Ruihan Li To: linux-bluetooth@vger.kernel.org Cc: Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , Ruihan Li Subject: [PATCH v2] Bluetooth: Fix potential double free caused by hci_conn_unlink Date: Mon, 1 May 2023 02:05:35 +0800 Message-Id: <20230430180535.168270-1-lrh2000@pku.edu.cn> X-Mailer: git-send-email 2.40.0 MIME-Version: 1.0 X-CM-TRANSID: 5oFpogBXX2f2rU5kiWv2AA--.57652S2 X-Coremail-Antispam: 1UD129KBjvJXoWxJrWkCrWrXrW8JryrKr1xXwb_yoW8tFWUpa y3WayaqF4kJrn3WF4jyw4kWrsYvw1kZFy7Kr1rtryrAws0qry8Aw4FkryUKrW5ZrWkWF4Y vF4Utr1UKF4DC37anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9j1xkIjI8I6I8E6xAIw20EY4v20xvaj40_Wr0E3s1l1IIY67AE w4v_Jr0_Jr4l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2 IY67AKxVW5JVW7JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwA2z4x0Y4vEx4A2 jsIE14v26F4UJVW0owA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Cr1j6rxdM2vYz4IE04k24V AvwVAKI4IrM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xf McIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7 v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7MxkIecxEwVCm -wCF04k20xvY0x0EwIxGrwCF04k20xvE74AGY7Cv6cx26w4UJr1UMxC20s026xCaFVCjc4 AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE 17CEb7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMI IF0xvE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4l IxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvf C2KfnxnUUI43ZEXa7VUbHa0DUUUUU== X-CM-SenderInfo: yssqiiarrvmko6sn3hxhgxhubq/1tbiAgEPBVPy77wh+AAKso Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org The hci_conn_unlink function is being called by hci_conn_del, which means it should not call hci_conn_del with the input parameter conn again. If it does, conn may have already been released when hci_conn_unlink returns, leading to potential UAF and double-free issues. This patch resolves the problem by modifying hci_conn_unlink to release only conn's child links when necessary, but never release conn itself. Fixes: 06149746e720 ("Bluetooth: hci_conn: Add support for linking multiple hcon") Signed-off-by: Ruihan Li Reported-by: syzbot+690b90b14f14f43f4688@syzkaller.appspotmail.com --- Changes since v1: * CI complains that there are some merge conflicts. This is because void hci_conn_del(struct hci_conn *conn) this completely unrelated line makes the patch dependent on another fix: https://lore.kernel.org/linux-bluetooth/20230430171847.156825-1-lrh2000@pku.edu.cn/ But actually, deleting that line makes the two patches independent of each other, and everything still works. net/bluetooth/hci_conn.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c index 85c34c837..5f388202f 100644 --- a/net/bluetooth/hci_conn.c +++ b/net/bluetooth/hci_conn.c @@ -1083,8 +1083,18 @@ static void hci_conn_unlink(struct hci_conn *conn) if (!conn->parent) { struct hci_link *link, *t; - list_for_each_entry_safe(link, t, &conn->link_list, list) - hci_conn_unlink(link->conn); + list_for_each_entry_safe(link, t, &conn->link_list, list) { + struct hci_conn *child = link->conn; + + hci_conn_unlink(child); + + /* Due to race, SCO connection might be not established + * yet at this point. Delete it now, otherwise it is + * possible for it to be stuck and can't be deleted. + */ + if (child->handle == HCI_CONN_HANDLE_UNSET) + hci_conn_del(child); + } return; } @@ -1100,12 +1110,5 @@ static void hci_conn_unlink(struct hci_conn *conn) kfree(conn->link); conn->link = NULL; - - /* Due to race, SCO connection might be not established - * yet at this point. Delete it now, otherwise it is - * possible for it to be stuck and can't be deleted. - */ - if (conn->handle == HCI_CONN_HANDLE_UNSET) - hci_conn_del(conn); }