From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1AE3C433EF for ; Sat, 4 Sep 2021 06:32:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 964AD60FD7 for ; Sat, 4 Sep 2021 06:32:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350862AbhIDGdy (ORCPT ); Sat, 4 Sep 2021 02:33:54 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:15384 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236308AbhIDGdx (ORCPT ); Sat, 4 Sep 2021 02:33:53 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4H1l9b5Rbtzbgqx; Sat, 4 Sep 2021 14:28:51 +0800 (CST) Received: from dggpemm500004.china.huawei.com (7.185.36.219) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Sat, 4 Sep 2021 14:32:49 +0800 Received: from huawei.com (10.175.124.27) by dggpemm500004.china.huawei.com (7.185.36.219) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Sat, 4 Sep 2021 14:32:48 +0800 From: Laibin Qiu To: , , CC: , , Subject: [PATCH -next] [SCSI] Fix NULL pointer dereference in handling for passthrough commands Date: Sat, 4 Sep 2021 14:45:34 +0800 Message-ID: <20210904064534.1919476-1-qiulaibin@huawei.com> X-Mailer: git-send-email 2.22.0 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.124.27] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500004.china.huawei.com (7.185.36.219) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In passthrough path. If the command size for ioctl request from userspace is 0. The original process will get cmd_len from cmd->cmnd, but It has not been assigned at this time. So it will trigger a NULL pointer BUG. ------------[ cut here ]------------ BUG: kernel NULL pointer dereference, address: 0000000000000000 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page RIP: 0010:scsi_queue_rq+0xcb2/0x12b0 Call Trace: blk_mq_dispatch_rq_list+0x541/0xe90 __blk_mq_sched_dispatch_requests+0x1fe/0x2b0 blk_mq_sched_dispatch_requests+0xbf/0x130 __blk_mq_run_hw_queue+0x15b/0x230 __blk_mq_delay_run_hw_queue+0x18f/0x320 blk_mq_run_hw_queue+0x252/0x280 blk_mq_sched_insert_request+0x228/0x260 blk_execute_rq+0x111/0x160 sg_io+0x51a/0x740 scsi_cmd_ioctl+0x533/0x910 scsi_cmd_blk_ioctl+0xa1/0xb0 cdrom_ioctl+0x3f/0x2510 sr_block_ioctl+0x142/0x180 blkdev_ioctl+0x398/0x450 block_ioctl+0x6d/0x80 __se_sys_ioctl+0xd1/0x140 __x64_sys_ioctl+0x3f/0x50 do_syscall_64+0x37/0x50 entry_SYSCALL_64_after_hwframe+0x44/0xa9 We can trigger front BUG by ioctl blow. ------------[ cut here ]------------ sg_io_hdr_t *addr; addr = malloc(sizeof(sg_io_hdr_t)); memset(addr, 0, sizeof(sg_io_hdr_t)); addr->interface_id = 'S'; fd = open(/dev/sr0, O_RDONLY); // open a CD_ROM dev ioctl(fd, SG_IO, addr); // all zero sg_io_hdr_t will trigger this bug Fixes: 2ceda20f0a99a ("scsi: core: Move command size detection out of the fast path") Signed-off-by: Laibin Qiu --- drivers/scsi/scsi_lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 572673873ddf..53b47a9103d3 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1174,9 +1174,9 @@ static blk_status_t scsi_setup_scsi_cmnd(struct scsi_device *sdev, } cmd->cmd_len = scsi_req(req)->cmd_len; + cmd->cmnd = scsi_req(req)->cmd; if (cmd->cmd_len == 0) cmd->cmd_len = scsi_command_size(cmd->cmnd); - cmd->cmnd = scsi_req(req)->cmd; cmd->transfersize = blk_rq_bytes(req); cmd->allowed = scsi_req(req)->retries; return BLK_STS_OK; -- 2.22.0