linux-stable.git/drivers/block/loop.c, branch v3.12.2

block: fix a probe argument to blk_register_region

2013-11-29T19:28:06+00:00

commit a207f5937630dd35bd2550620bef416937a1365e upstream.

The probe function is supposed to return NULL on failure (as we can see in
kobj_lookup: kobj = probe(dev, index, data); ... if (kobj) return kobj;

However, in loop and brd, it returns negative error from ERR_PTR.

This causes a crash if we simulate disk allocation failure and run
less -f /dev/loop0 because the negative number is interpreted as a pointer:

BUG: unable to handle kernel NULL pointer dereference at 00000000000002b4
IP: [] __blkdev_get+0x28/0x450
PGD 23c677067 PUD 23d6d1067 PMD 0
Oops: 0000 [#1] PREEMPT SMP
Modules linked in: loop hpfs nvidia(PO) ip6table_filter ip6_tables uvesafb cfbcopyarea cfbimgblt cfbfillrect fbcon font bitblit fbcon_rotate fbcon_cw fbcon_ud fbcon_ccw softcursor fb fbdev msr ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_conntrack_ipv4 nf_defrag_ipv4 xt_state ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp llc tun ipv6 cpufreq_stats cpufreq_ondemand cpufreq_userspace cpufreq_powersave cpufreq_conservative hid_generic spadfs usbhid hid fuse raid0 snd_usb_audio snd_pcm_oss snd_mixer_oss md_mod snd_pcm snd_timer snd_page_alloc snd_hwdep snd_usbmidi_lib dmi_sysfs snd_rawmidi nf_nat_ftp nf_nat nf_conntrack_ftp nf_conntrack snd soundcore lm85 hwmon_vid ohci_hcd ehci_pci ehci_hcd serverworks sata_svw libata acpi_cpufreq freq_table mperf ide_core usbcore kvm_amd kvm tg3 i2c_piix4 libphy microcode e100 usb_common ptp skge i2c_core pcspkr k10temp evdev floppy hwmon pps_core mii rtc_cmos button processor unix [last unloaded: nvidia]
CPU: 1 PID: 6831 Comm: less Tainted: P        W  O 3.10.15-devel #18
Hardware name: empty empty/S3992-E, BIOS 'V1.06   ' 06/09/2009
task: ffff880203cc6bc0 ti: ffff88023e47c000 task.ti: ffff88023e47c000
RIP: 0010:[]  [] __blkdev_get+0x28/0x450
RSP: 0018:ffff88023e47dbd8  EFLAGS: 00010286
RAX: ffffffffffffff74 RBX: ffffffffffffff74 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff88023e47dc18 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88023f519658
R13: ffffffff8118c300 R14: 0000000000000000 R15: ffff88023f519640
FS:  00007f2070bf7700(0000) GS:ffff880247400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000002b4 CR3: 000000023da1d000 CR4: 00000000000007e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Stack:
 0000000000000002 0000001d00000000 000000003e47dc50 ffff88023f519640
 ffff88043d5bb668 ffffffff8118c300 ffff88023d683550 ffff88023e47de60
 ffff88023e47dc98 ffffffff8118c10d 0000001d81605698 0000000000000292
Call Trace:
 [] ? blkdev_get_by_dev+0x60/0x60
 [] blkdev_get+0x1dd/0x370
 [] ? blkdev_get_by_dev+0x60/0x60
 [] ? _raw_spin_unlock+0x2c/0x50
 [] ? blkdev_get_by_dev+0x60/0x60
 [] blkdev_open+0x65/0x80
 [] do_dentry_open.isra.18+0x23e/0x2f0
 [] finish_open+0x34/0x50
 [] do_last.isra.62+0x2d2/0xc50
 [] path_openat.isra.63+0xb8/0x4d0
 [] ? might_fault+0x4e/0xa0
 [] do_filp_open+0x40/0x90
 [] ? _raw_spin_unlock+0x2c/0x50
 [] ? __alloc_fd+0xa5/0x1f0
 [] do_sys_open+0xef/0x1d0
 [] SyS_open+0x19/0x20
 [] system_call_fastpath+0x1a/0x1f
Code: 44 00 00 55 48 89 e5 41 57 49 89 ff 41 56 41 89 d6 41 55 41 54 4c 8d 67 18 53 48 83 ec 18 89 75 cc e9 f2 00 00 00 0f 1f 44 00 00 <48> 8b 80 40 03 00 00 48 89 df 4c 8b 68 58 e8 d5
a4 07 00 44 89
RIP  [] __blkdev_get+0x28/0x450
 RSP 
CR2: 00000000000002b4
---[ end trace bb7f32dbf02398dc ]---

The brd change should be backported to stable kernels starting with 2.6.25.
The loop change should be backported to stable kernels starting with 2.6.22.

Signed-off-by: Mikulas Patocka 
Acked-by: Tejun Heo 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

move linux/loop.h to drivers/block

2013-06-29T08:46:45+00:00

Signed-off-by: Al Viro

block_device_operations->release() should return void

2013-05-07T06:16:21+00:00

The value passed is 0 in all but "it can never happen" cases (and those
only in a couple of drivers) *and* it would've been lost on the way
out anyway, even if something tried to pass something meaningful.
Just don't bother.

Signed-off-by: Al Viro

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2013-05-02T00:51:54+00:00

Pull VFS updates from Al Viro,

Misc cleanups all over the place, mainly wrt /proc interfaces (switch
create_proc_entry to proc_create(), get rid of the deprecated
create_proc_read_entry() in favor of using proc_create_data() and
seq_file etc).

7kloc removed.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (204 commits)
  don't bother with deferred freeing of fdtables
  proc: Move non-public stuff from linux/proc_fs.h to fs/proc/internal.h
  proc: Make the PROC_I() and PDE() macros internal to procfs
  proc: Supply a function to remove a proc entry by PDE
  take cgroup_open() and cpuset_open() to fs/proc/base.c
  ppc: Clean up scanlog
  ppc: Clean up rtas_flash driver somewhat
  hostap: proc: Use remove_proc_subtree()
  drm: proc: Use remove_proc_subtree()
  drm: proc: Use minor->index to label things, not PDE->name
  drm: Constify drm_proc_list[]
  zoran: Don't print proc_dir_entry data in debug
  reiserfs: Don't access the proc_dir_entry in r_open(), r_start() r_show()
  proc: Supply an accessor for getting the data from a PDE's parent
  airo: Use remove_proc_subtree()
  rtl8192u: Don't need to save device proc dir PDE
  rtl8187se: Use a dir under /proc/net/r8180/
  proc: Add proc_mkdir_data()
  proc: Move some bits from linux/proc_fs.h to linux/{of.h,signal.h,tty.h}
  proc: Move PDE_NET() to fs/proc/proc_net.c
  ...

Merge tag 'for-linus-20130409' of git://git.kernel.dk/linux-block

2013-04-09T19:05:41+00:00

Pull block fixes from Jens Axboe:
 "I've got a few smaller fixes queued up for 3.9 that should go in.  The
  major one is the loop regression, the others are nice fixes on their
  own though.  It contains:

   - Fix for unitialized var in the block sysfs code, courtesy of Arnd
     and gcc-4.8.

   - Two fixes for mtip32xx, fixing probe and command timeout.  Also a
     debug measure that could have waited for 3.10, but it's driver
     only, so I let it slip in.

   - Revert the loop partition cleanup fix, it could cause a deadlock on
     auto-teardown as part of umount.  The fix is clear, but at this
     point we just want to revert it and get a real fix in for 3.10."

* tag 'for-linus-20130409' of git://git.kernel.dk/linux-block:
  Revert "loop: cleanup partitions when detaching loop device"
  mtip32xx: fix two smatch warnings
  mtip32xx: Add debugfs entry device_status
  mtip32xx: return 0 from pci probe in case of rebuild
  mtip32xx: recovery from command timeout
  block: avoid using uninitialized value in from queue_var_store

lift sb_start_write() out of ->write()

2013-04-09T18:12:56+00:00

Signed-off-by: Al Viro

Revert "loop: cleanup partitions when detaching loop device"

2013-04-08T08:12:11+00:00

This reverts commit 8761a3dc1f07b163414e2215a2cadbb4cfe2a107.

There are situations where the destruction path is called
with the bdev->bd_mutex already held, which then deadlocks in
loop_clr_fd(). The normal partition cleanup does a trylock()
on the mutex, but it'd be nice to have a more bullet proof
method in loop. So punt this more involved fix to the next
merge window, and just back out this buggy fix for now.

Signed-off-by: Jens Axboe

loop: prevent bdev freeing while device in use

2013-04-01T22:48:47+00:00

struct block_device lifecycle is defined by its inode (see fs/block_dev.c) -
block_device allocated first time we access /dev/loopXX and deallocated on
bdev_destroy_inode. When we create the device "losetup /dev/loopXX afile"
we want that block_device stay alive until we destroy the loop device
with "losetup -d".

But because we do not hold /dev/loopXX inode its counter goes 0, and
inode/bdev can be destroyed at any moment. Usually it happens at memory
pressure or when user drops inode cache (like in the test below). When later in
loop_clr_fd() we want to use bdev we have use-after-free error with following
stack:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000280
  bd_set_size+0x10/0xa0
  loop_clr_fd+0x1f8/0x420 [loop]
  lo_ioctl+0x200/0x7e0 [loop]
  lo_compat_ioctl+0x47/0xe0 [loop]
  compat_blkdev_ioctl+0x341/0x1290
  do_filp_open+0x42/0xa0
  compat_sys_ioctl+0xc1/0xf20
  do_sys_open+0x16e/0x1d0
  sysenter_dispatch+0x7/0x1a

To prevent use-after-free we need to grab the device in loop_set_fd()
and put it later in loop_clr_fd().

The issue is reprodusible on current Linus head and v3.3. Here is the test:

  dd if=/dev/zero of=loop.file bs=1M count=1
  while [ true ]; do
    losetup /dev/loop0 loop.file
    echo 2 > /proc/sys/vm/drop_caches
    losetup -d /dev/loop0
  done

[ Doing bdgrab/bput in loop_set_fd/loop_clr_fd is safe, because every
  time we call loop_set_fd() we check that loop_device->lo_state is
  Lo_unbound and set it to Lo_bound If somebody will try to set_fd again
  it will get EBUSY.  And if we try to loop_clr_fd() on unbound loop
  device we'll get ENXIO.

  loop_set_fd/loop_clr_fd (and any other loop ioctl) is called under
  loop_device->lo_ctl_mutex. ]

Signed-off-by: Anatol Pomozov 
Cc: Al Viro 
Signed-off-by: Linus Torvalds

loop: cleanup partitions when detaching loop device

2013-03-22T18:21:53+00:00

Any partitions added by user space to the loop device were being
left in place after detaching the loop device.  This was because
the detach path issued a BLKRRPART to clean up partitions if
LO_FLAGS_PARTSCAN was set, meaning that the partitions were auto
scanned on attach.  Replace this BLKRRPART with code that
unconditionally cleans up partitions on detach instead.

Signed-off-by: Phillip Susi 

Modified by Jens to export delete_partition().

Signed-off-by: Jens Axboe

loop: fix error return code in loop_add()

2013-03-22T14:59:19+00:00

Fix to return a negative error code from the error handling
case, as returned elsewhere in this function.

Signed-off-by: Wei Yongjun 
Signed-off-by: Jens Axboe