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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 CDA7FC33CAD for ; Mon, 13 Jan 2020 11:05:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A10DF2081E for ; Mon, 13 Jan 2020 11:05:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Zoo2zPQU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726934AbgAMLFE (ORCPT ); Mon, 13 Jan 2020 06:05:04 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:24458 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726193AbgAMLFD (ORCPT ); Mon, 13 Jan 2020 06:05:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578913502; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=LEHXgkhJ8pPH8e10XArdPGNvW/iZvMmKPNjc2LR34xs=; b=Zoo2zPQUsvv6+28mp0cF09NQVS0GKgpbKw+BUZSmVjLqpLlAkUwbKtvbDHNEyHp1mVn8XB MUlk3usvLHe+zbt0cSBw7RXKVTejWBFiw17y/dlFVzp1x0rkVXvNDBqpSFgz8wy1rXjGs4 SZUl8Vc+T5ZT4vOPRKV2kL3ZeuvO/LE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-250-OiiZe9bONmGbjzi_qzWBYA-1; Mon, 13 Jan 2020 06:04:59 -0500 X-MC-Unique: OiiZe9bONmGbjzi_qzWBYA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 042271B18BDE; Mon, 13 Jan 2020 11:04:58 +0000 (UTC) Received: from ming.t460p (ovpn-8-29.pek2.redhat.com [10.72.8.29]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0CBB95C1BB; Mon, 13 Jan 2020 11:04:50 +0000 (UTC) Date: Mon, 13 Jan 2020 19:04:46 +0800 From: Ming Lei To: Zhiqiang Liu Cc: Jens Axboe , linux-block@vger.kernel.org, "linux-kernel@vger.kernel.org" , npiggin@suse.de, Mingfangsen , Guiyao , zhangsaisai , "wubo (T)" Subject: Re: [PATCH] brd: check parameter validation before register_blkdev func Message-ID: <20200113110003.GA13011@ming.t460p> References: <342ee238-0e7c-c213-eecc-7062f24985cc@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <342ee238-0e7c-c213-eecc-7062f24985cc@huawei.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, Jan 10, 2020 at 01:10:20PM +0800, Zhiqiang Liu wrote: > > 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_par_valid func to check parameter > validation before register_blkdev func. > > Signed-off-by: Zhiqiang Liu > --- > drivers/block/brd.c | 33 ++++++++++++++++++++++++++------- > 1 file changed, 26 insertions(+), 7 deletions(-) > > diff --git a/drivers/block/brd.c b/drivers/block/brd.c > index df8103dd40ac..3a4510b2c24f 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"); > @@ -468,10 +468,25 @@ static struct kobject *brd_probe(dev_t dev, int *part, void *data) > return kobj; > } > > +static inline int brd_check_par_valid(void) > +{ > + if (unlikely(!rd_nr)) > + rd_nr = 1; > + > + if (unlikely(!max_part)) > + max_part = 1; > + > + if (rd_nr * max_part > MINORMASK) > + return -EINVAL; > + > + return 0; > + > +} > + > static int __init brd_init(void) > { > struct brd_device *brd, *next; > - int i; > + int i, ret; > > /* > * brd module now has a feature to instantiate underlying device > @@ -488,11 +503,15 @@ static int __init brd_init(void) > * dynamically. > */ > > + ret = brd_check_par_valid(); > + if (ret) { > + pr_info("brd: invalid parameter setting!!!\n"); > + return ret; > + } > + The max supported partition number is 256, see __alloc_disk_node(). So even though one bigger number is passed to alloc_disk(), at most 256 partitions are allowed on that disk. Maybe you can apply the following way to avoid the issue: disk->first_minor = i * disk->minors; However, looks 'rd_nr' still needs to be validated(rd_nr < 2 ^ 23). Thanks, Ming