linux-stable.git/drivers/md, branch v4.4.53

md linear: fix a race between linear_add() and linear_congested()

2017-03-12T05:37:30+00:00

commit 03a9e24ef2aaa5f1f9837356aed79c860521407a upstream.

Recently I receive a bug report that on Linux v3.0 based kerenl, hot add
disk to a md linear device causes kernel crash at linear_congested(). From
the crash image analysis, I find in linear_congested(), mddev->raid_disks
contains value N, but conf->disks[] only has N-1 pointers available. Then
a NULL pointer deference crashes the kernel.

There is a race between linear_add() and linear_congested(), RCU stuffs
used in these two functions cannot avoid the race. Since Linuv v4.0
RCU code is replaced by introducing mddev_suspend().  After checking the
upstream code, it seems linear_congested() is not called in
generic_make_request() code patch, so mddev_suspend() cannot provent it
from being called. The possible race still exists.

Here I explain how the race still exists in current code.  For a machine
has many CPUs, on one CPU, linear_add() is called to add a hard disk to a
md linear device; at the same time on other CPU, linear_congested() is
called to detect whether this md linear device is congested before issuing
an I/O request onto it.

Now I use a possible code execution time sequence to demo how the possible
race happens,

seq    linear_add()                linear_congested()
 0                                 conf=mddev->private
 1   oldconf=mddev->private
 2   mddev->raid_disks++
 3                              for (i=0; iraid_disks;i++)
 4                                bdev_get_queue(conf->disks[i].rdev->bdev)
 5   mddev->private=newconf

In linear_add() mddev->raid_disks is increased in time seq 2, and on
another CPU in linear_congested() the for-loop iterates conf->disks[i] by
the increased mddev->raid_disks in time seq 3,4. But conf with one more
element (which is a pointer to struct dev_info type) to conf->disks[] is
not updated yet, accessing its structure member in time seq 4 will cause a
NULL pointer deference fault.

To fix this race, there are 2 parts of modification in the patch,
 1) Add 'int raid_disks' in struct linear_conf, as a copy of
    mddev->raid_disks. It is initialized in linear_conf(), always being
    consistent with pointers number of 'struct dev_info disks[]'. When
    iterating conf->disks[] in linear_congested(), use conf->raid_disks to
    replace mddev->raid_disks in the for-loop, then NULL pointer deference
    will not happen again.
 2) RCU stuffs are back again, and use kfree_rcu() in linear_add() to
    free oldconf memory. Because oldconf may be referenced as mddev->private
    in linear_congested(), kfree_rcu() makes sure that its memory will not
    be released until no one uses it any more.
Also some code comments are added in this patch, to make this modification
to be easier understandable.

This patch can be applied for kernels since v4.0 after commit:
3be260cc18f8 ("md/linear: remove rcu protections in favour of
suspend/resume"). But this bug is reported on Linux v3.0 based kernel, for
people who maintain kernels before Linux v4.0, they need to do some back
back port to this patch.

Changelog:
 - V3: add 'int raid_disks' in struct linear_conf, and use kfree_rcu() to
       replace rcu_call() in linear_add().
 - v2: add RCU stuffs by suggestion from Shaohua and Neil.
 - v1: initial effort.

Signed-off-by: Coly Li 
Cc: Shaohua Li 
Cc: Neil Brown 
Signed-off-by: Shaohua Li 
Signed-off-by: Greg Kroah-Hartman

dm stats: fix a leaked s->histogram_boundaries array

2017-03-12T05:37:26+00:00

commit 6085831883c25860264721df15f05bbded45e2a2 upstream.

Fixes: dfcfac3e4cd9 ("dm stats: collect and report histogram of IO latencies")
Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman

dm cache: fix corruption seen when using cache > 2TB

2017-03-12T05:37:26+00:00

commit ca763d0a53b264a650342cee206512bc92ac7050 upstream.

A rounding bug due to compiler generated temporary being 32bit was found
in remap_to_cache().  A localized cast in remap_to_cache() fixes the
corruption but this preferred fix (changing from uint32_t to sector_t)
eliminates potential for future rounding errors elsewhere.

Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman

bcache: Make gc wakeup sane, remove set_task_state()

2017-02-23T16:43:10+00:00

commit be628be09563f8f6e81929efbd7cf3f45c344416 upstream.

Signed-off-by: Kent Overstreet 
Signed-off-by: Greg Kroah-Hartman

md: MD_RECOVERY_NEEDED is set for mddev->recovery

2017-01-12T10:22:50+00:00

commit 82a301cb0ea2df8a5c88213094a01660067c7fb4 upstream.

Fixes: 90f5f7ad4f38("md: Wait for md_check_recovery before attempting device
removal.")

Reviewed-by: NeilBrown 
Signed-off-by: Shaohua Li 
Signed-off-by: Greg Kroah-Hartman

md/raid5: limit request size according to implementation limits

2017-01-09T07:07:49+00:00

commit e8d7c33232e5fdfa761c3416539bc5b4acd12db5 upstream.

Current implementation employ 16bit counter of active stripes in lower
bits of bio->bi_phys_segments. If request is big enough to overflow
this counter bio will be completed and freed too early.

Fortunately this not happens in default configuration because several
other limits prevent that: stripe_cache_size * nr_disks effectively
limits count of active stripes. And small max_sectors_kb at lower
disks prevent that during normal read/write operations.

Overflow easily happens in discard if it's enabled by module parameter
"devices_handle_discard_safely" and stripe_cache_size is set big enough.

This patch limits requests size with 256Mb - 8Kb to prevent overflows.

Signed-off-by: Konstantin Khlebnikov 
Cc: Shaohua Li 
Cc: Neil Brown 
Signed-off-by: Shaohua Li 
Signed-off-by: Greg Kroah-Hartman

dm space map metadata: fix 'struct sm_metadata' leak on failed create

2017-01-06T10:16:15+00:00

commit 314c25c56c1ee5026cf99c570bdfe01847927acb upstream.

In dm_sm_metadata_create() we temporarily change the dm_space_map
operations from 'ops' (whose .destroy function deallocates the
sm_metadata) to 'bootstrap_ops' (whose .destroy function doesn't).

If dm_sm_metadata_create() fails in sm_ll_new_metadata() or
sm_ll_extend(), it exits back to dm_tm_create_internal(), which calls
dm_sm_destroy() with the intention of freeing the sm_metadata, but it
doesn't (because the dm_space_map operations is still set to
'bootstrap_ops').

Fix this by setting the dm_space_map operations back to 'ops' if
dm_sm_metadata_create() fails when it is set to 'bootstrap_ops'.

Signed-off-by: Benjamin Marzinski 
Acked-by: Joe Thornber 
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman

dm crypt: mark key as invalid until properly loaded

2017-01-06T10:16:15+00:00

commit 265e9098bac02bc5e36cda21fdbad34cb5b2f48d upstream.

In crypt_set_key(), if a failure occurs while replacing the old key
(e.g. tfm->setkey() fails) the key must not have DM_CRYPT_KEY_VALID flag
set.  Otherwise, the crypto layer would have an invalid key that still
has DM_CRYPT_KEY_VALID flag set.

Signed-off-by: Ondrej Kozina 
Reviewed-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman

dm flakey: return -EINVAL on interval bounds error in flakey_ctr()

2017-01-06T10:16:15+00:00

commit bff7e067ee518f9ed7e1cbc63e4c9e01670d0b71 upstream.

Fix to return error code -EINVAL instead of 0, as is done elsewhere in
this function.

Fixes: e80d1c805a3b ("dm: do not override error code returned from dm_get_device()")
Signed-off-by: Wei Yongjun 
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman

dm mirror: fix read error on recovery after default leg failure

2016-11-10T15:36:35+00:00

commit dcb2ff56417362c31f6b430c3c531a84581e8721 upstream.

If a default leg has failed, any read will cause a new operational
default leg to be selected and the read is resubmitted.  But until now
the read will return failure even though it was successful due to
resubmission.  The reason for this is bio->bi_error was not being
cleared before resubmitting the bio.

Fix by clearing bio->bi_error before resubmission.

Fixes: 4246a0b63bd8 ("block: add a bi_error field to struct bio")
Signed-off-by: Heinz Mauelshagen 
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman