linux-toradex.git/block, branch v3.3-rc2

cfq-iosched: fix use-after-free of cfqq

2012-01-17T20:26:11+00:00

With the changes in life time management between the cfq IO contexts
and the cfq queues, we now risk having cfqd->active_queue being
freed when cfq_slice_expired() is being called. cfq_preempt_queue()
caches this queue and uses it after calling said function, causing
a use-after-free condition. This triggers the following oops,
when cfqq_type() attempts to dereference it:

BUG: unable to handle kernel paging request at ffff8800746c4f0c
IP: [] cfqq_type+0xb/0x20
PGD 18d4063 PUD 1fe15067 PMD 1ffb9067 PTE 80000000746c4160
Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
CPU 3
Modules linked in:

Pid: 1, comm: init Not tainted 3.2.0-josef+ #367 Bochs Bochs
RIP: 0010:[]  [] cfqq_type+0xb/0x20
RSP: 0018:ffff880079c11778  EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff880076f3df08 RCX: 0000000000000000
RDX: 0000000000000006 RSI: ffff880074271888 RDI: ffff8800746c4f08
RBP: ffff880079c11778 R08: 0000000000000078 R09: 0000000000000001
R10: 09f911029d74e35b R11: 09f911029d74e35b R12: ffff880076f337f0
R13: ffff8800746c4f08 R14: ffff8800746c4f08 R15: 0000000000000002
FS:  00007f62fd44f700(0000) GS:ffff88007cd80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff8800746c4f0c CR3: 0000000076c21000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process init (pid: 1, threadinfo ffff880079c10000, task ffff880079c0a040)
Stack:
 ffff880079c117c8 ffffffff812683d8 ffff880079c117a8 ffffffff8125de43
 ffff8800744fcf48 ffff880074b43e98 ffff8800770c8828 ffff880074b43e98
 0000000000000003 0000000000000000 ffff880079c117f8 ffffffff81254149
Call Trace:
 [] cfq_insert_request+0x3f5/0x47c
 [] ? blk_recount_segments+0x20/0x31
 [] __elv_add_request+0x1ca/0x200
 [] blk_queue_bio+0x2ef/0x312
 [] generic_make_request+0x9f/0xe0
 [] submit_bio+0xbf/0xca
 [] submit_bh+0xdf/0xfe
 [] ext3_bread+0x50/0x99
 [] dx_probe+0x38/0x291
 [] ext3_dx_find_entry+0x58/0x219
 [] ext3_find_entry+0xb0/0x406
 [] ? cache_alloc_debugcheck_after.isra.46+0x14d/0x1a0
 [] ? kmem_cache_alloc+0xef/0x191
 [] ext3_lookup+0x39/0xe1
 [] d_alloc_and_lookup+0x45/0x6c
 [] do_lookup+0x1e4/0x2f5
 [] link_path_walk+0x1a4/0x6ef
 [] path_lookupat+0x59/0x5ea
 [] ? __strncpy_from_user+0x30/0x5a
 [] do_path_lookup+0x23/0x59
 [] user_path_at_empty+0x53/0x99
 [] ? remove_wait_queue+0x51/0x56
 [] user_path_at+0x11/0x13
 [] vfs_fstatat+0x3a/0x64
 [] vfs_stat+0x1b/0x1d
 [] sys_newstat+0x1a/0x33
 [] ? task_stopped_code+0x42/0x42
 [] system_call_fastpath+0x16/0x1b
Code: 89 e6 48 89 c7 e8 fa ca fe ff 85 c0 74 06 4c 89 2b 41 b6 01 5b 44 89 f0 41 5c 41 5d 41 5e 5d c3 55 48 89 e5 66 66 66 66 90 31 c0 <8b> 57 04 f6 c6 01 74 0b 83 e2 20 83 fa 01 19 c0 83 c0 02 5d c3
RIP  [] cfqq_type+0xb/0x20
 RSP 
CR2: ffff8800746c4f0c

Get rid of the caching of cfqd->active_queue, and reorder the
check so that it happens before we expire the active queue.

Thanks to Tejun for pin pointing the error location.

Reported-by: Chris Mason 
Tested-by: Chris Mason 
Signed-off-by: Jens Axboe

Merge branch 'for-3.3/core' of git://git.kernel.dk/linux-block

2012-01-15T20:24:45+00:00

* 'for-3.3/core' of git://git.kernel.dk/linux-block: (37 commits)
  Revert "block: recursive merge requests"
  block: Stop using macro stubs for the bio data integrity calls
  blockdev: convert some macros to static inlines
  fs: remove unneeded plug in mpage_readpages()
  block: Add BLKROTATIONAL ioctl
  block: Introduce blk_set_stacking_limits function
  block: remove WARN_ON_ONCE() in exit_io_context()
  block: an exiting task should be allowed to create io_context
  block: ioc_cgroup_changed() needs to be exported
  block: recursive merge requests
  block, cfq: fix empty queue crash caused by request merge
  block, cfq: move icq creation and rq->elv.icq association to block core
  block, cfq: restructure io_cq creation path for io_context interface cleanup
  block, cfq: move io_cq exit/release to blk-ioc.c
  block, cfq: move icq cache management to block core
  block, cfq: move io_cq lookup to blk-ioc.c
  block, cfq: move cfqd->icq_list to request_queue and add request->elv.icq
  block, cfq: reorganize cfq_io_context into generic and cfq specific parts
  block: remove elevator_queue->ops
  block: reorder elevator switch sequence
  ...

Fix up conflicts in:
 - block/blk-cgroup.c
	Switch from can_attach_task to can_attach
 - block/cfq-iosched.c
	conflict with now removed cic index changes (we now use q->id instead)

Revert "block: recursive merge requests"

2012-01-15T09:29:48+00:00

This reverts commit 274193224cdabd687d804a26e0150bb20f2dd52c.

We have some problems related to selection of empty queues
that need to be resolved, evidence so far points to the
recursive merge logic making either being the cause or at
least the accelerator for this. So revert it for now, until
we figure this out.

Signed-off-by: Jens Axboe

block: fail SCSI passthrough ioctls on partition devices

2012-01-14T23:07:24+00:00

Linux allows executing the SG_IO ioctl on a partition or LVM volume, and
will pass the command to the underlying block device.  This is
well-known, but it is also a large security problem when (via Unix
permissions, ACLs, SELinux or a combination thereof) a program or user
needs to be granted access only to part of the disk.

This patch lets partitions forward a small set of harmless ioctls;
others are logged with printk so that we can see which ioctls are
actually sent.  In my tests only CDROM_GET_CAPABILITY actually occurred.
Of course it was being sent to a (partition on a) hard disk, so it would
have failed with ENOTTY and the patch isn't changing anything in
practice.  Still, I'm treating it specially to avoid spamming the logs.

In principle, this restriction should include programs running with
CAP_SYS_RAWIO.  If for example I let a program access /dev/sda2 and
/dev/sdb, it still should not be able to read/write outside the
boundaries of /dev/sda2 independent of the capabilities.  However, for
now programs with CAP_SYS_RAWIO will still be allowed to send the
ioctls.  Their actions will still be logged.

This patch does not affect the non-libata IDE driver.  That driver
however already tests for bd != bd->bd_contains before issuing some
ioctl; it could be restricted further to forbid these ioctls even for
programs running with CAP_SYS_ADMIN/CAP_SYS_RAWIO.

Cc: linux-scsi@vger.kernel.org
Cc: Jens Axboe 
Cc: James Bottomley 
Signed-off-by: Paolo Bonzini 
[ Make it also print the command name when warning - Linus ]
Signed-off-by: Linus Torvalds

block: add and use scsi_blk_cmd_ioctl

2012-01-14T23:07:24+00:00

Introduce a wrapper around scsi_cmd_ioctl that takes a block device.

The function will then be enhanced to detect partition block devices
and, in that case, subject the ioctls to whitelisting.

Cc: linux-scsi@vger.kernel.org
Cc: Jens Axboe 
Cc: James Bottomley 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Linus Torvalds

block: Add BLKROTATIONAL ioctl

2012-01-11T15:29:31+00:00

Introduce an ioctl which permits applications to query whether a block
device is rotational.

Signed-off-by: Martin K. Petersen 
Signed-off-by: Jens Axboe

block: Introduce blk_set_stacking_limits function

2012-01-11T15:27:11+00:00

Stacking driver queue limits are typically bounded exclusively by the
capabilities of the low level devices, not by the stacking driver
itself.

This patch introduces blk_set_stacking_limits() which has more liberal
metrics than the default queue limits function. This allows us to
inherit topology parameters from bottom devices without manually
tweaking the default limits in each driver prior to calling the stacking
function.

Since there is now a clear distinction between stacking and low-level
devices, blk_set_default_limits() has been modified to carry the more
conservative values that we used to manually set in
blk_queue_make_request().

Signed-off-by: Martin K. Petersen 
Acked-by: Mike Snitzer 
Signed-off-by: Jens Axboe

Merge branch 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2012-01-09T20:59:24+00:00

* 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits)
  cgroup: fix to allow mounting a hierarchy by name
  cgroup: move assignement out of condition in cgroup_attach_proc()
  cgroup: Remove task_lock() from cgroup_post_fork()
  cgroup: add sparse annotation to cgroup_iter_start() and cgroup_iter_end()
  cgroup: mark cgroup_rmdir_waitq and cgroup_attach_proc() as static
  cgroup: only need to check oldcgrp==newgrp once
  cgroup: remove redundant get/put of task struct
  cgroup: remove redundant get/put of old css_set from migrate
  cgroup: Remove unnecessary task_lock before fetching css_set on migration
  cgroup: Drop task_lock(parent) on cgroup_fork()
  cgroups: remove redundant get/put of css_set from css_set_check_fetched()
  resource cgroups: remove bogus cast
  cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task()
  cgroup, cpuset: don't use ss->pre_attach()
  cgroup: don't use subsys->can_attach_task() or ->attach_task()
  cgroup: introduce cgroup_taskset and use it in subsys->can_attach(), cancel_attach() and attach()
  cgroup: improve old cgroup handling in cgroup_attach_proc()
  cgroup: always lock threadgroup during migration
  threadgroup: extend threadgroup_lock() to cover exit and exec
  threadgroup: rename signal->threadgroup_fork_lock to ->group_rwsem
  ...

Fix up conflict in kernel/cgroup.c due to commit e0197aae59e5: "cgroups:
fix a css_set not found bug in cgroup_attach_proc" that already
mentioned that the bug is fixed (differently) in Tejun's cgroup
patchset. This one, in other words.

Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2012-01-08T20:19:57+00:00

* 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (165 commits)
  reiserfs: Properly display mount options in /proc/mounts
  vfs: prevent remount read-only if pending removes
  vfs: count unlinked inodes
  vfs: protect remounting superblock read-only
  vfs: keep list of mounts for each superblock
  vfs: switch ->show_options() to struct dentry *
  vfs: switch ->show_path() to struct dentry *
  vfs: switch ->show_devname() to struct dentry *
  vfs: switch ->show_stats to struct dentry *
  switch security_path_chmod() to struct path *
  vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb
  vfs: trim includes a bit
  switch mnt_namespace ->root to struct mount
  vfs: take /proc/*/mounts and friends to fs/proc_namespace.c
  vfs: opencode mntget() mnt_set_mountpoint()
  vfs: spread struct mount - remaining argument of next_mnt()
  vfs: move fsnotify junk to struct mount
  vfs: move mnt_devname
  vfs: move mnt_list to struct mount
  vfs: switch pnode.h macros to struct mount *
  ...

Merge branches 'vfsmount-guts', 'umode_t' and 'partitions' into Z

2012-01-07T04:15:54+00:00