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Alexey Dobriyan cf6e693212 loop: fix NULL dereference if mount fails 
Commit bb21488482 ("[PATCH] switch loop")
started to pass NULL bdev to ioctl hook.

Steps to reproduce:

	[boot with loop.max_part=1]
	[mount -o loop something so mount fails]

BUG: unable to handle kernel NULL pointer dereference at 00000000000000b8
IP: [<ffffffff811486ee>] blkdev_ioctl+0x2e/0xa30
PGD 0
Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
last sysfs file: /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:35/ACPI0003:00/power_supply/ACAD/online
CPU 0
Modules linked in: zfs nvidia(P) [last unloaded: zfs]
Pid: 15177, comm: mount Tainted: P           2.6.32-rc4-zfs #2 Satellite X200
RIP: 0010:[<ffffffff811486ee>]  [<ffffffff811486ee>] blkdev_ioctl+0x2e/0xa30
RSP: 0018:ffff88003b3d5bb8  EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 000000000000125f RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88003b3d5ce8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 00007ffffffff000
R13: 0000000000000000 R14: ffff880071cef280 R15: 00000000000200da
FS:  00007fd77cfe7740(0000) GS:ffff880001600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000000000000b8 CR3: 0000000001001000 CR4: 00000000000026f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process mount (pid: 15177, threadinfo ffff88003b3d4000, task ffff88007572f920)
Stack:
 ffff88003b3d5c38 ffffffff812f95f5 ffff88007eeb6600 0000000000000000
<0> 0000000000000000 ffff88003b3d5c18 ffffffff811547d9 ffff88001bf11ef0
<0> 7fffffffffffffff ffff88001bf11ee8 ffff88001bf11ef0 0000000000000000
Call Trace:
 [<ffffffff812f95f5>] ? schedule_timeout+0x1f5/0x250
 [<ffffffff811547d9>] ? rb_insert_color+0x109/0x140
 [<ffffffff812fb754>] ? _spin_unlock_irq+0x14/0x40
 [<ffffffff812f84c6>] ? wait_for_common+0x66/0x170
 [<ffffffff8105a280>] ? default_wake_function+0x0/0x10
 [<ffffffff810f8258>] ioctl_by_bdev+0x38/0x50
 [<ffffffff811d2481>] loop_clr_fd+0x1e1/0x210
 [<ffffffff811d2522>] lo_release+0x72/0x80
 [<ffffffff810f934c>] __blkdev_put+0x1ac/0x1d0
 [<ffffffff810f937b>] blkdev_put+0xb/0x10
 [<ffffffff810f93b9>] blkdev_close+0x39/0x60
 [<ffffffff810ccef3>] __fput+0xd3/0x230
 [<ffffffff810cd06d>] fput+0x1d/0x30
 [<ffffffff810c9680>] filp_close+0x50/0x80
 [<ffffffff81061f11>] put_files_struct+0x81/0x100
 [<ffffffff81061fde>] exit_files+0x4e/0x60
 [<ffffffff81063ec5>] do_exit+0x6b5/0x730
 [<ffffffff8107b279>] ? up_read+0x9/0x10
 [<ffffffff8104c86e>] ? do_page_fault+0x18e/0x2a0
 [<ffffffff81063f81>] do_group_exit+0x41/0xc0
 [<ffffffff81064012>] sys_exit_group+0x12/0x20
 [<ffffffff81030deb>] system_call_fastpath+0x16/0x1b
Code: f8 48 89 e5 48 81 ec 30 01 00 00 48 89 5d d8 4c 89 6d e8 4c 89 65 e0 4c 89 75 f0 4c 89 7d f8 48 89 bd e8 fe ff ff 49 89 cd 89 f3 <49> 8b 88 b8 00 00 00 81 fa 68 12 00 00 0f 84 57 05 00 00 0f 86
RIP  [<ffffffff811486ee>] blkdev_ioctl+0x2e/0xa30
 RSP <ffff88003b3d5bb8>
CR2: 00000000000000b8
---[ end trace c0b4d3c3118d1427 ]---
Fixing recursive fault but reboot is needed!

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-10-29 07:39:27 -07:00
..
aoe const: make block_device_operations const 2009-09-22 07:17:25 -07:00
paride const: make block_device_operations const 2009-09-22 07:17:25 -07:00
amiflop.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
ataflop.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
brd.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
cciss_cmd.h cciss: Ignore stale commands after reboot 2009-07-03 21:06:45 +02:00
cciss_scsi.c cciss: decode unit attention in SCSI error handling code 2009-06-09 05:47:44 +02:00
cciss_scsi.h
cciss.c cciss: Add cciss_allow_hpsa module parameter 2009-10-13 09:18:22 +02:00
cciss.h cciss: Dynamically allocate the drive_info_struct for each logical drive. 2009-10-01 21:15:45 +02:00
cpqarray.c cpqarray: switch to seq_file 2009-10-01 21:15:40 +02:00
cpqarray.h
cryptoloop.c
DAC960.c dac960: switch to seq_file 2009-10-01 21:15:40 +02:00
DAC960.h
floppy.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
hd.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
ida_cmd.h
ida_ioctl.h
Kconfig osdblk: a Linux block device for OSD objects 2009-06-24 12:25:02 +03:00
loop.c loop: fix NULL dereference if mount fails 2009-10-29 07:39:27 -07:00
Makefile osdblk: a Linux block device for OSD objects 2009-06-24 12:25:02 +03:00
mg_disk.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
nbd.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
osdblk.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
pktcdvd.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
ps3disk.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
ps3vram.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
smart1,2.h
sunvdc.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
swim3.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-09-22 07:51:45 -07:00
swim_asm.S m68k: mac - Add SWIM floppy support 2009-03-26 21:15:27 +01:00
swim.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
sx8.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
ub.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
umem.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
umem.h
viodasd.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
virtio_blk.c virtio_blk: Revert serial number support 2009-10-22 16:39:30 +10:30
xd.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
xd.h
xen-blkfront.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
xsysace.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00
z2ram.c const: make block_device_operations const 2009-09-22 07:17:25 -07:00