From patchwork Tue Dec 26 07:43:55 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: 13504812 Received: from buaa.edu.cn (unknown [202.112.128.25]) (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 1AD5F4C60B; Tue, 26 Dec 2023 07:44:09 +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="yLy0OXQ3" 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=yLy0OXQ3HrJv7RPMCHKVztNoi1 SCyFWpggxuDkTKrcejdxNG6Zc84Ysf7NdczCIviLlc1oEgClg2jPwe/V9Jn7cWxU LTRrjKxx4HPVv92u/qD541HngsGRlGODWBVtG8KpdvS6WfhYtZIjaBsEhoFimFP7 rvEc+DejfPjkizVLs= Received: from localhost.localdomain (unknown [10.130.147.18]) by coremail-app1 (Coremail) with SMTP id OCz+CgDnGFtAhIplSSWCAA--.2391S2; Tue, 26 Dec 2023 15:44:01 +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 rfcomm_check_security Date: Tue, 26 Dec 2023 15:43:55 +0800 Message-Id: <20231226074355.328940-1-20373622@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+CgDnGFtAhIplSSWCAA--.2391S2 X-Coremail-Antispam: 1UD129KBjvJXoW7WFyDGF1xXr18Aw4UCw4rXwb_yoW8Zr45p3 9Fya4fKFn5JrnxAF1kA3WkCFyrZr4v9F1Utr4Fv3yYy3s8W34xtrWSkr1Uua45CFs0y34x ZF10qa9xGFnrC3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBF1xkIjI8I6I8E6xAIw20EY4v20xvaj40_Wr0E3s1l1IIY67AE w4v_Jr0_Jr4l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2 IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr1UM28EF7xvwVC2 z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0DM2vYz4IE04k24V AvwVAKI4IrM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xf McIj6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7 v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7MxkF7I0En4kS 14v26r126r1DMxkIecxEwVCm-wCF04k20xvY0x0EwIxGrwCF04k20xvE74AGY7Cv6cx26F 1DJr1UJwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E 7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcV C0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF 04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7 CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUp7KsUUUUU= 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);