nbd: limit module parameters to a sane value
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).
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@gmail.com>
Cc: Laurent Vivier <Laurent.Vivier@bull.net>
Cc: Paul Clements <Paul.Clements@steeleye.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 1df3bfe..fdee756 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -757,6 +757,12 @@
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)