From patchwork Tue Feb 4 02:44:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhiqiang Liu X-Patchwork-Id: 11363915 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7457F112B for ; Tue, 4 Feb 2020 02:44:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5C5732086A for ; Tue, 4 Feb 2020 02:44:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726853AbgBDCo1 (ORCPT ); Mon, 3 Feb 2020 21:44:27 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:10146 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726561AbgBDCo1 (ORCPT ); Mon, 3 Feb 2020 21:44:27 -0500 Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id B9A3A66404176C707E8E; Tue, 4 Feb 2020 10:44:25 +0800 (CST) Received: from [127.0.0.1] (10.173.220.183) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.439.0; Tue, 4 Feb 2020 10:44:19 +0800 To: Ming Lei , Jens Axboe CC: , , Mingfangsen , "wubo (T)" , Guiyao , Yanxiaodan From: Zhiqiang Liu Subject: [PATCH V5] brd: check and limit max_part par Message-ID: <3f053491-d8c1-7092-58d1-85afaa2e68df@huawei.com> Date: Tue, 4 Feb 2020 10:44:18 +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-Language: en-US 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. Reviewed-by: Ming Lei --- V4->V5:(suggested by Ming Lei) - make sure max_part is not larger than DISK_MAX_PARTS V3->V4:(suggested by Ming Lei) - remove useless change - add one limit of max_part 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 Reviewed-by: Bob Liu --- drivers/block/brd.c | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index df8103dd40ac..6b9db3f63cb7 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -389,11 +389,12 @@ static struct brd_device *brd_alloc(int i) * is harmless) */ blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE); - disk = brd->brd_disk = alloc_disk(max_part); + disk = brd->brd_disk = alloc_disk(((i * max_part) & ~MINORMASK) ? + 0 : max_part); if (!disk) goto out_free_queue; disk->major = RAMDISK_MAJOR; - disk->first_minor = i * max_part; + disk->first_minor = i * disk->minors; disk->fops = &brd_fops; disk->private_data = brd; disk->queue = brd->brd_queue; @@ -468,6 +469,25 @@ 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(!max_part)) + max_part = 1; + + /* + * make sure 'max_part' can be divided exactly by (1U << MINORBITS), + * otherwise, it is possiable to get same dev_t when adding partitions. + */ + if ((1U << MINORBITS) % max_part != 0) + max_part = 1UL << fls(max_part); + + 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 +511,7 @@ 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);