linux-stable.git/drivers/md, branch v3.2.99

dm bufio: fix integer overflow when limiting maximum cache size

2018-02-13T18:32:17+00:00

commit 74d4108d9e681dbbe4a2940ed8fdff1f6868184c upstream.

The default max_cache_size_bytes for dm-bufio is meant to be the lesser
of 25% of the size of the vmalloc area and 2% of the size of lowmem.
However, on 32-bit systems the intermediate result in the expression

    (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100

overflows, causing the wrong result to be computed.  For example, on a
32-bit system where the vmalloc area is 520093696 bytes, the result is
1174405 rather than the expected 130023424, which makes the maximum
cache size much too small (far less than 2% of lowmem).  This causes
severe performance problems for dm-verity users on affected systems.

Fix this by using mult_frac() to correctly multiply by a percentage.  Do
this for all places in dm-bufio that multiply by a percentage.  Also
replace (VMALLOC_END - VMALLOC_START) with VMALLOC_TOTAL, which contrary
to the comment is now defined in include/linux/vmalloc.h.

Depends-on: 9993bc635 ("sched/x86: Fix overflow in cyc2ns_offset")
Fixes: 95d402f057f2 ("dm: add bufio")
Signed-off-by: Eric Biggers 
Signed-off-by: Mike Snitzer 
[bwh: Backported to 3.2: keep open-coded VMALLOC_TOTAL]
Signed-off-by: Ben Hutchings

dm: discard support requires all targets in a table support discards

2018-02-13T18:32:17+00:00

commit 8a74d29d541cd86569139c6f3f44b2d210458071 upstream.

A DM device with a mix of discard capabilities (due to some underlying
devices not having discard support) _should_ just return -EOPNOTSUPP for
the region of the device that doesn't support discards (even if only by
way of the underlying driver formally not supporting discards).  BUT,
that does ask the underlying driver to handle something that it never
advertised support for.  In doing so we're exposing users to the
potential for a underlying disk driver hanging if/when a discard is
issued a the device that is incapable and never claimed to support
discards.

Fix this by requiring that each DM target in a DM table provide discard
support as a prereq for a DM device to advertise support for discards.

This may cause some configurations that were happily supporting discards
(even in the face of a mix of discard support) to stop supporting
discards -- but the risk of users hitting driver hangs, and forced
reboots, outweighs supporting those fringe mixed discard
configurations.

Signed-off-by: Mike Snitzer 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

dm: fix race between dm_get_from_kobject() and __dm_destroy()

2018-02-13T18:32:15+00:00

commit b9a41d21dceadf8104812626ef85dc56ee8a60ed upstream.

The following BUG_ON was hit when testing repeat creation and removal of
DM devices:

    kernel BUG at drivers/md/dm.c:2919!
    CPU: 7 PID: 750 Comm: systemd-udevd Not tainted 4.1.44
    Call Trace:
     [] dm_get_from_kobject+0x34/0x3a
     [] dm_attr_show+0x2b/0x5e
     [] ? mutex_lock+0x26/0x44
     [] sysfs_kf_seq_show+0x83/0xcf
     [] kernfs_seq_show+0x23/0x25
     [] seq_read+0x16f/0x325
     [] kernfs_fop_read+0x3a/0x13f
     [] __vfs_read+0x26/0x9d
     [] ? security_file_permission+0x3c/0x44
     [] ? rw_verify_area+0x83/0xd9
     [] vfs_read+0x8f/0xcf
     [] ? __fdget_pos+0x12/0x41
     [] SyS_read+0x4b/0x76
     [] system_call_fastpath+0x12/0x71

The bug can be easily triggered, if an extra delay (e.g. 10ms) is added
between the test of DMF_FREEING & DMF_DELETING and dm_get() in
dm_get_from_kobject().

To fix it, we need to ensure the test of DMF_FREEING & DMF_DELETING and
dm_get() are done in an atomic way, so _minor_lock is used.

The other callers of dm_get() have also been checked to be OK: some
callers invoke dm_get() under _minor_lock, some callers invoke it under
_hash_lock, and dm_start_request() invoke it after increasing
md->open_count.

Signed-off-by: Hou Tao 
Signed-off-by: Mike Snitzer 
Signed-off-by: Ben Hutchings

dm: fix printk() rate limiting code

2017-11-11T13:34:33+00:00

commit 604407890ecf624c2fb41013c82b22aade59b455 upstream.

Using the same rate limiting state for different kinds of messages
is wrong because this can cause a high frequency message to suppress
a report of a low frequency message. Hence use a unique rate limiting
state per message type.

Fixes: 71a16736a15e ("dm: use local printk ratelimit")
Signed-off-by: Bart Van Assche 
Signed-off-by: Mike Snitzer 
Signed-off-by: Ben Hutchings

md: don't use flush_signals in userspace processes

2017-10-12T14:27:10+00:00

commit f9c79bc05a2a91f4fba8bfd653579e066714b1ec upstream.

The function flush_signals clears all pending signals for the process. It
may be used by kernel threads when we need to prepare a kernel thread for
responding to signals. However using this function for an userspaces
processes is incorrect - clearing signals without the program expecting it
can cause misbehavior.

The raid1 and raid5 code uses flush_signals in its request routine because
it wants to prepare for an interruptible wait. This patch drops
flush_signals and uses sigprocmask instead to block all signals (including
SIGKILL) around the schedule() call. The signals are not lost, but the
schedule() call won't respond to them.

Signed-off-by: Mikulas Patocka 
Acked-by: NeilBrown 
Signed-off-by: Shaohua Li 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

md: ensure md devices are freed before module is unloaded.

2017-06-05T20:13:48+00:00

commit 9356863c9409efc79029c01a85d015efae977e69 upstream.

Commit: cbd199837750 ("md: Fix unfortunate interaction with evms")
change mddev_put() so that it would not destroy an md device while
->ctime was non-zero.

Unfortunately, we didn't make sure to clear ->ctime when unloading
the module, so it is possible for an md device to remain after
module unload.  An attempt to open such a device will trigger
an invalid memory reference in:
  get_gendisk -> kobj_lookup -> exact_lock -> get_disk

when tring to access disk->fops, which was in the module that has
been removed.

So ensure we clear ->ctime in md_exit(), and explain how that is useful,
as it isn't immediately obvious when looking at the code.

Fixes: cbd199837750 ("md: Fix unfortunate interaction with evms")
Tested-by: Guoqing Jiang 
Signed-off-by: NeilBrown 
Signed-off-by: Shaohua Li 
Signed-off-by: Ben Hutchings

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

2017-06-05T20:13:48+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 
[bwh: Backported to 3.2: no need to restore RCU protections]
Signed-off-by: Ben Hutchings

dm crypt: mark key as invalid until properly loaded

2017-03-16T02:18:27+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: Ben Hutchings

dm table: fix missing dm_put_target_type() in dm_table_add_target()

2017-02-23T03:50:54+00:00

commit dafa724bf582181d9a7d54f5cb4ca0bf8ef29269 upstream.

dm_get_target_type() was previously called so any error returned from
dm_table_add_target() must first call dm_put_target_type().  Otherwise
the DM target module's reference count will leak and the associated
kernel module will be unable to be removed.

Also, leverage the fact that r is already -EINVAL and remove an extra
newline.

Fixes: 36a0456 ("dm table: add immutable feature")
Fixes: cc6cbe1 ("dm table: add always writeable feature")
Fixes: 3791e2f ("dm table: add singleton feature")
Signed-off-by: tang.junhui 
Signed-off-by: Mike Snitzer 
[bwh: Backported to 3.2: adjuat context]
Signed-off-by: Ben Hutchings

dm flakey: error READ bios during the down_interval

2016-11-20T01:01:30+00:00

commit 99f3c90d0d85708e7401a81ce3314e50bf7f2819 upstream.

When the corrupt_bio_byte feature was introduced it caused READ bios to
no longer be errored with -EIO during the down_interval.  This had to do
with the complexity of needing to submit READs if the corrupt_bio_byte
feature was used.

Fix it so READ bios are properly errored with -EIO; doing so early in
flakey_map() as long as there isn't a match for the corrupt_bio_byte
feature.

Fixes: a3998799fb4df ("dm flakey: add corrupt_bio_byte feature")
Reported-by: Akira Hayakawa 
Signed-off-by: Mike Snitzer 
[bwh: Backported to 3.2: in flakey_end_io(), keep using
 bio_submitted_while_down instead of pb->bio_submitted]
Signed-off-by: Ben Hutchings