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Date: Fri, 27 May 2011 08:41:06 -0400 From: Paul Clements <paul.clements@...sios.com> To: Namhyung Kim <namhyung@...il.com> Cc: Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org, Laurent Vivier <Laurent.Vivier@...l.net>, stable@...nel.org Subject: Re: [PATCH 2/3] nbd: limit module parameters to a sane value On Fri, May 27, 2011 at 2:00 AM, Namhyung Kim <namhyung@...il.com> 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:[<ffffffff8115aa08>] [<ffffffff8115aa08>] 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: > [<ffffffff812e8f6e>] ? device_add+0x4f1/0x5e4 > [<ffffffff812e7a80>] ? dev_set_name+0x41/0x43 > [<ffffffff8115ab6a>] sysfs_create_group+0x13/0x15 > [<ffffffff810b857e>] blk_trace_init_sysfs+0x14/0x16 > [<ffffffff811ee58b>] blk_register_queue+0x4c/0xfd > [<ffffffff811f3bdf>] add_disk+0xe4/0x29c > [<ffffffffa007e2ab>] nbd_init+0x2ab/0x30d [nbd] > [<ffffffffa007e000>] ? 0xffffffffa007dfff > [<ffffffff8100020f>] do_one_initcall+0x7f/0x13e > [<ffffffff8107ab0a>] sys_init_module+0xa1/0x1e3 > [<ffffffff814f3542>] 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 [<ffffffff8115aa08>] internal_create_group+0x2f/0x166 > RSP <ffff8801009f1de8> > ---[ end trace 753285ffbf72c57c ]--- > > Signed-off-by: Namhyung Kim <namhyung@...il.com> > Cc: Laurent Vivier <Laurent.Vivier@...l.net> > Cc: Paul Clements <Paul.Clements@...eleye.com> > Cc: stable@...nel.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 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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