From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755517Ab1E0MlL (ORCPT ); Fri, 27 May 2011 08:41:11 -0400 Received: from mail-iw0-f174.google.com ([209.85.214.174]:50513 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754217Ab1E0MlH convert rfc822-to-8bit (ORCPT ); Fri, 27 May 2011 08:41:07 -0400 MIME-Version: 1.0 In-Reply-To: <1306476003-4624-2-git-send-email-namhyung@gmail.com> References: <1306476003-4624-1-git-send-email-namhyung@gmail.com> <1306476003-4624-2-git-send-email-namhyung@gmail.com> Date: Fri, 27 May 2011 08:41:06 -0400 Message-ID: Subject: Re: [PATCH 2/3] nbd: limit module parameters to a sane value From: Paul Clements To: Namhyung Kim Cc: Jens Axboe , linux-kernel@vger.kernel.org, Laurent Vivier , stable@kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 27, 2011 at 2:00 AM, Namhyung Kim wrote: > The 'max_part' parameter controls the number of maximum partition > a nbd device can have. However if a user specifies very large > value it would exceed the limitation of device minor number and > can cause a kernel oops (or, at least, produce invalid device > nodes in some cases). Then don't do that... :) Patch looks good. Thanks, Paul > In addition, specifying large 'nbds_max' value causes same > problem for the same reason. > > On my desktop, following command results to the kernel bug: > > $ sudo modprobe nbd max_part=100000 >  kernel BUG at /media/Linux_Data/project/linux/fs/sysfs/group.c:65! >  invalid opcode: 0000 [#1] SMP >  last sysfs file: /sys/devices/virtual/block/nbd4/range >  CPU 1 >  Modules linked in: nbd(+) bridge stp llc kvm_intel kvm asus_atk0110 sg sr_mod cdrom > >  Pid: 2522, comm: modprobe Tainted: G        W   2.6.39-leonard+ #159 System manufacturer System Product Name/P5G41TD-M PRO >  RIP: 0010:[]  [] internal_create_group+0x2f/0x166 >  RSP: 0018:ffff8801009f1de8  EFLAGS: 00010246 >  RAX: 00000000ffffffef RBX: ffff880103920478 RCX: 00000000000a7bd3 >  RDX: ffffffff81a2dbe0 RSI: 0000000000000000 RDI: ffff880103920478 >  RBP: ffff8801009f1e38 R08: ffff880103920468 R09: ffff880103920478 >  R10: ffff8801009f1de8 R11: ffff88011eccbb68 R12: ffffffff81a2dbe0 >  R13: ffff880103920468 R14: 0000000000000000 R15: ffff880103920400 >  FS:  00007f3c49de9700(0000) GS:ffff88011f800000(0000) knlGS:0000000000000000 >  CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b >  CR2: 00007f3b7fe7c000 CR3: 00000000cd58d000 CR4: 00000000000406e0 >  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >  DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 >  Process modprobe (pid: 2522, threadinfo ffff8801009f0000, task ffff8801009a93a0) >  Stack: >  ffff8801009f1e58 ffffffff812e8f6e ffff8801009f1e58 ffffffff812e7a80 >  ffff880000000010 ffff880103920400 ffff8801002fd0c0 ffff880103920468 >  0000000000000011 ffff880103920400 ffff8801009f1e48 ffffffff8115ab6a >  Call Trace: >  [] ? device_add+0x4f1/0x5e4 >  [] ? dev_set_name+0x41/0x43 >  [] sysfs_create_group+0x13/0x15 >  [] blk_trace_init_sysfs+0x14/0x16 >  [] blk_register_queue+0x4c/0xfd >  [] add_disk+0xe4/0x29c >  [] nbd_init+0x2ab/0x30d [nbd] >  [] ? 0xffffffffa007dfff >  [] do_one_initcall+0x7f/0x13e >  [] sys_init_module+0xa1/0x1e3 >  [] system_call_fastpath+0x16/0x1b >  Code: 41 57 41 56 41 55 41 54 53 48 83 ec 28 0f 1f 44 00 00 48 89 fb 41 89 f6 49 89 d4 48 85 ff 74 0b 85 f6 75 0b 48 83 >  7f 30 00 75 14 <0f> 0b eb fe b9 ea ff ff ff 48 83 7f 30 00 0f 84 09 01 00 00 49 >  RIP  [] internal_create_group+0x2f/0x166 >  RSP >  ---[ end trace 753285ffbf72c57c ]--- > > Signed-off-by: Namhyung Kim > Cc: Laurent Vivier > Cc: Paul Clements > Cc: stable@kernel.org > --- >  drivers/block/nbd.c |    6 ++++++ >  1 files changed, 6 insertions(+), 0 deletions(-) > > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c > index 1df3bfe5225b..fdee7567fd15 100644 > --- a/drivers/block/nbd.c > +++ b/drivers/block/nbd.c > @@ -757,6 +757,12 @@ static int __init nbd_init(void) >        if (max_part > 0) >                part_shift = fls(max_part); > > +       if ((1UL << part_shift) > DISK_MAX_PARTS) > +               return -EINVAL; > + > +       if (nbds_max > 1UL << (MINORBITS - part_shift)) > +               return -EINVAL; > + >        for (i = 0; i < nbds_max; i++) { >                struct gendisk *disk = alloc_disk(1 << part_shift); >                if (!disk) > -- > 1.7.5.2 > >