From patchwork Tue Dec 26 07:39:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yuxuan Hu <20373622@buaa.edu.cn> X-Patchwork-Id: 13504811 Received: from azure-sdnproxy.icoremail.net (azure-sdnproxy.icoremail.net [52.237.72.81]) by smtp.subspace.kernel.org (Postfix) with ESMTP id F37FF4CB38; Tue, 26 Dec 2023 07:40:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=buaa.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=buaa.edu.cn Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=buaa.edu.cn header.i=@buaa.edu.cn header.b="EbPVD5WF" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=buaa.edu.cn; s=buaa; h=Received:From:To:Cc:Subject:Date: Message-Id:MIME-Version:Content-Transfer-Encoding; bh=CBFS7CfXR8 wjJT32lD2LRnMsaDbQhnnj+E/AiAFNbl4=; b=EbPVD5WF5WSYknHZZfWZDlTC+h PiFykKsa10I9OuIogWaR71xfEX4oMvV+yRUSHw0gjdl0JlVaoQS/fV4M/JN55Bkc fBMN259ajm71TwEVyvG+NHJbWjT5AV3VSxwT1eyhUHiHyOCOCZrT3zJFIzIH0VX2 6QgaVjK9rs+McZKNg= Received: from localhost.localdomain (unknown [10.130.147.18]) by coremail-app1 (Coremail) with SMTP id OCz+CgB3p1lPg4pljSKCAA--.64158S2; Tue, 26 Dec 2023 15:40:00 +0800 (CST) From: Yuxuan Hu <20373622@buaa.edu.cn> To: marcel@holtmann.org, johan.hedberg@gmail.com, luiz.dentz@gmail.com Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, sy2239101@buaa.edu.cn, Yuxuan Hu <20373622@buaa.edu.cn> Subject: [PATCH] Bluetooth: rfcomm: Fix null-ptr-deref in Date: Tue, 26 Dec 2023 15:39:57 +0800 Message-Id: <20231226073957.328124-1-20373622@buaa.edu.cn> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-bluetooth@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: OCz+CgB3p1lPg4pljSKCAA--.64158S2 X-Coremail-Antispam: 1UD129KBjvJXoW7WFyDGF1xXr18Aw4UCw4rXwb_yoW8Zr45p3 9Fya4fKFn5JrnxAF1kA3WkCFyrZr4v9F1Utr4Fv3yYy3s8W34xtrWSkr1Uua45CFs0y34x ZF10qa9xGFnrC3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9j1xkIjI8I6I8E6xAIw20EY4v20xvaj40_Wr0E3s1l1IIY67AE w4v_Jr0_Jr4l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2 IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr1UM28EF7xvwVC2 z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0DM2vYz4IE04k24V AvwVAKI4IrM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xf McIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7 v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7MxkIecxEwVCm -wCF04k20xvY0x0EwIxGrwCF04k20xvE74AGY7Cv6cx26F1DJr1UJwCFx2IqxVCFs4IE7x kEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E 67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCw CI42IY6xIIjxv20xvEc7CjxVAFwI0_Jr0_Gr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1x MIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Jr0_GrUvcSsGvf C2KfnxnUUI43ZEXa7VUbHa0DUUUUU== X-CM-SenderInfo: ysqtljawssquxxddhvlgxou0/ During our fuzz testing of the connection and disconnection process at the RFCOMM layer,we discovered this bug.By comparing the packetsfrom a normal connection and disconnection process with the testcase that triggered a KASAN report, we analyzed the cause of this bug as follows: 1. In the packets captured during a normal connection, the host sends a `Read Encryption Key Size` type of `HCI_CMD` packet(Command Opcode: 0x1408) to the controller to inquire the length of encryption key.After receiving this packet, the controller immediately replies with a Command Complete packet (Event Code: 0x0e) to return the Encryption Key Size. 2. In our fuzz test case, the timing of the controller's response to this packet was delayed to an unexpected point: after the RFCOMM and L2CAP layers had disconnected but before the HCI layer had disconnected. 3. After receiving the Encryption Key Size Response at the time described in point 2, the host still called the rfcomm_check_security function. However, by this time `struct l2cap_conn *conn = l2cap_pi(sk)->chan->conn;` had already been released, and when the function executed `return hci_conn_security(conn->hcon, d->sec_level, auth_type, d->out);`, specifically when accessing `conn->hcon`, a null-ptr-deref error occurred. Adding a check for whether `conn` is a null pointer to fix this bug. Signed-off-by: Yuxuan Hu <20373622@buaa.edu.cn> --- net/bluetooth/rfcomm/core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c index 053ef8f25fae..5ffa197fdb48 100644 --- a/net/bluetooth/rfcomm/core.c +++ b/net/bluetooth/rfcomm/core.c @@ -228,6 +228,9 @@ static int rfcomm_check_security(struct rfcomm_dlc *d) auth_type = HCI_AT_NO_BONDING; break; } + + if (!conn) + return 0; return hci_conn_security(conn->hcon, d->sec_level, auth_type, d->out);