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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 54655C33CB1 for ; Tue, 14 Jan 2020 11:56:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2E26324679 for ; Tue, 14 Jan 2020 11:56:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728899AbgANL4S (ORCPT ); Tue, 14 Jan 2020 06:56:18 -0500 Received: from szxga06-in.huawei.com ([45.249.212.32]:45548 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725956AbgANL4S (ORCPT ); Tue, 14 Jan 2020 06:56:18 -0500 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 5C6C283E77F513A02D3A; Tue, 14 Jan 2020 19:56:16 +0800 (CST) Received: from [127.0.0.1] (10.173.220.183) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.439.0; Tue, 14 Jan 2020 19:56:09 +0800 To: Ming Lei , Jens Axboe CC: , "linux-kernel@vger.kernel.org" , Mingfangsen , Guiyao , zhangsaisai , "wubo (T)" From: Zhiqiang Liu Subject: [PATCH V3] brd: check and limit max_part par Message-ID: Date: Tue, 14 Jan 2020 19:56:07 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.173.220.183] X-CFilter-Loop: Reflected Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org In brd_init func, rd_nr num of brd_device are firstly allocated and add in brd_devices, then brd_devices are traversed to add each brd_device by calling add_disk func. When allocating brd_device, the disk->first_minor is set to i * max_part, if rd_nr * max_part is larger than MINORMASK, two different brd_device may have the same devt, then only one of them can be successfully added. when rmmod brd.ko, it will cause oops when calling brd_exit. Follow those steps: # modprobe brd rd_nr=3 rd_size=102400 max_part=1048576 # rmmod brd then, the oops will appear. Oops log: [ 726.613722] Call trace: [ 726.614175] kernfs_find_ns+0x24/0x130 [ 726.614852] kernfs_find_and_get_ns+0x44/0x68 [ 726.615749] sysfs_remove_group+0x38/0xb0 [ 726.616520] blk_trace_remove_sysfs+0x1c/0x28 [ 726.617320] blk_unregister_queue+0x98/0x100 [ 726.618105] del_gendisk+0x144/0x2b8 [ 726.618759] brd_exit+0x68/0x560 [brd] [ 726.619501] __arm64_sys_delete_module+0x19c/0x2a0 [ 726.620384] el0_svc_common+0x78/0x130 [ 726.621057] el0_svc_handler+0x38/0x78 [ 726.621738] el0_svc+0x8/0xc [ 726.622259] Code: aa0203f6 aa0103f7 aa1e03e0 d503201f (7940e260) Here, we add brd_check_and_reset_par func to check and limit max_part par. -- V2->V3: (suggested by Ming Lei) - clear .minors when running out of consecutive minor space in brd_alloc - remove limit of rd_nr V1->V2: add more checks in brd_check_par_valid as suggested by Ming Lei. Signed-off-by: Zhiqiang Liu --- drivers/block/brd.c | 35 ++++++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index df8103dd40ac..2295a0bafb5e 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -330,16 +330,16 @@ static const struct block_device_operations brd_fops = { /* * And now the modules code and kernel interface. */ -static int rd_nr = CONFIG_BLK_DEV_RAM_COUNT; -module_param(rd_nr, int, 0444); +static unsigned int rd_nr = CONFIG_BLK_DEV_RAM_COUNT; +module_param(rd_nr, uint, 0444); MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices"); unsigned long rd_size = CONFIG_BLK_DEV_RAM_SIZE; module_param(rd_size, ulong, 0444); MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes."); -static int max_part = 1; -module_param(max_part, int, 0444); +static unsigned int max_part = 1; +module_param(max_part, uint, 0444); MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices"); MODULE_LICENSE("GPL"); @@ -393,7 +393,14 @@ static struct brd_device *brd_alloc(int i) if (!disk) goto out_free_queue; disk->major = RAMDISK_MAJOR; - disk->first_minor = i * max_part; + /* + * Clear .minors when running out of consecutive minor space since + * GENHD_FL_EXT_DEVT is set, and we can allocate from extended devt. + */ + if ((i * disk->minors) & ~MINORMASK) + disk->minors = 0; + else + disk->first_minor = i * disk->minors; disk->fops = &brd_fops; disk->private_data = brd; disk->queue = brd->brd_queue; @@ -468,6 +475,21 @@ static struct kobject *brd_probe(dev_t dev, int *part, void *data) return kobj; } +static inline void brd_check_and_reset_par(void) +{ + if (unlikely(!rd_nr)) + rd_nr = 1; + + if (unlikely(!max_part)) + max_part = 1; + + if (max_part > DISK_MAX_PARTS) { + pr_info("brd: max_part can't be larger than %d, reset max_part = %d.\n", + DISK_MAX_PARTS, DISK_MAX_PARTS); + max_part = DISK_MAX_PARTS; + } +} + static int __init brd_init(void) { struct brd_device *brd, *next; @@ -491,8 +513,7 @@ static int __init brd_init(void) if (register_blkdev(RAMDISK_MAJOR, "ramdisk")) return -EIO; - if (unlikely(!max_part)) - max_part = 1; + brd_check_and_reset_par(); for (i = 0; i < rd_nr; i++) { brd = brd_alloc(i); -- 2.19.1