From 3b2710824e00d238554c13b5add347e6c701ab1a Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Sat, 28 May 2011 14:44:46 +0200 Subject: [PATCH] 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:[] [] 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 Signed-off-by: Jens Axboe --- drivers/block/nbd.c | 6 ++++++ 1 file changed, 6 insertions(+) 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 @@ 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) -- 2.7.4