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  1. 16 7月, 2020 3 次提交
  3. 09 7月, 2020 1 次提交
  5. 01 7月, 2020 4 次提交
  7. 24 6月, 2020 1 次提交
  9. 18 6月, 2020 1 次提交
  11. 17 6月, 2020 1 次提交
    • J
      block: Fix use-after-free in blkdev_get() · 2d3a8e2d
      由 Jason Yan 提交于 
      In blkdev_get() we call __blkdev_get() to do some internal jobs and if
there is some errors in __blkdev_get(), the bdput() is called which
means we have released the refcount of the bdev (actually the refcount of
the bdev inode). This means we cannot access bdev after that point. But
acctually bdev is still accessed in blkdev_get() after calling
__blkdev_get(). This results in use-after-free if the refcount is the
last one we released in __blkdev_get(). Let's take a look at the
following scenerio:

  CPU0            CPU1                    CPU2
blkdev_open     blkdev_open           Remove disk
                  bd_acquire
		  blkdev_get
		    __blkdev_get      del_gendisk
					bdev_unhash_inode
  bd_acquire          bdev_get_gendisk
    bd_forget           failed because of unhashed
	  bdput
	              bdput (the last one)
		        bdev_evict_inode

	  	    access bdev => use after free

[  459.350216] BUG: KASAN: use-after-free in __lock_acquire+0x24c1/0x31b0
[  459.351190] Read of size 8 at addr ffff88806c815a80 by task syz-executor.0/20132
[  459.352347]
[  459.352594] CPU: 0 PID: 20132 Comm: syz-executor.0 Not tainted 4.19.90 #2
[  459.353628] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[  459.354947] Call Trace:
[  459.355337]  dump_stack+0x111/0x19e
[  459.355879]  ? __lock_acquire+0x24c1/0x31b0
[  459.356523]  print_address_description+0x60/0x223
[  459.357248]  ? __lock_acquire+0x24c1/0x31b0
[  459.357887]  kasan_report.cold+0xae/0x2d8
[  459.358503]  __lock_acquire+0x24c1/0x31b0
[  459.359120]  ? _raw_spin_unlock_irq+0x24/0x40
[  459.359784]  ? lockdep_hardirqs_on+0x37b/0x580
[  459.360465]  ? _raw_spin_unlock_irq+0x24/0x40
[  459.361123]  ? finish_task_switch+0x125/0x600
[  459.361812]  ? finish_task_switch+0xee/0x600
[  459.362471]  ? mark_held_locks+0xf0/0xf0
[  459.363108]  ? __schedule+0x96f/0x21d0
[  459.363716]  lock_acquire+0x111/0x320
[  459.364285]  ? blkdev_get+0xce/0xbe0
[  459.364846]  ? blkdev_get+0xce/0xbe0
[  459.365390]  __mutex_lock+0xf9/0x12a0
[  459.365948]  ? blkdev_get+0xce/0xbe0
[  459.366493]  ? bdev_evict_inode+0x1f0/0x1f0
[  459.367130]  ? blkdev_get+0xce/0xbe0
[  459.367678]  ? destroy_inode+0xbc/0x110
[  459.368261]  ? mutex_trylock+0x1a0/0x1a0
[  459.368867]  ? __blkdev_get+0x3e6/0x1280
[  459.369463]  ? bdev_disk_changed+0x1d0/0x1d0
[  459.370114]  ? blkdev_get+0xce/0xbe0
[  459.370656]  blkdev_get+0xce/0xbe0
[  459.371178]  ? find_held_lock+0x2c/0x110
[  459.371774]  ? __blkdev_get+0x1280/0x1280
[  459.372383]  ? lock_downgrade+0x680/0x680
[  459.373002]  ? lock_acquire+0x111/0x320
[  459.373587]  ? bd_acquire+0x21/0x2c0
[  459.374134]  ? do_raw_spin_unlock+0x4f/0x250
[  459.374780]  blkdev_open+0x202/0x290
[  459.375325]  do_dentry_open+0x49e/0x1050
[  459.375924]  ? blkdev_get_by_dev+0x70/0x70
[  459.376543]  ? __x64_sys_fchdir+0x1f0/0x1f0
[  459.377192]  ? inode_permission+0xbe/0x3a0
[  459.377818]  path_openat+0x148c/0x3f50
[  459.378392]  ? kmem_cache_alloc+0xd5/0x280
[  459.379016]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  459.379802]  ? path_lookupat.isra.0+0x900/0x900
[  459.380489]  ? __lock_is_held+0xad/0x140
[  459.381093]  do_filp_open+0x1a1/0x280
[  459.381654]  ? may_open_dev+0xf0/0xf0
[  459.382214]  ? find_held_lock+0x2c/0x110
[  459.382816]  ? lock_downgrade+0x680/0x680
[  459.383425]  ? __lock_is_held+0xad/0x140
[  459.384024]  ? do_raw_spin_unlock+0x4f/0x250
[  459.384668]  ? _raw_spin_unlock+0x1f/0x30
[  459.385280]  ? __alloc_fd+0x448/0x560
[  459.385841]  do_sys_open+0x3c3/0x500
[  459.386386]  ? filp_open+0x70/0x70
[  459.386911]  ? trace_hardirqs_on_thunk+0x1a/0x1c
[  459.387610]  ? trace_hardirqs_off_caller+0x55/0x1c0
[  459.388342]  ? do_syscall_64+0x1a/0x520
[  459.388930]  do_syscall_64+0xc3/0x520
[  459.389490]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  459.390248] RIP: 0033:0x416211
[  459.390720] Code: 75 14 b8 02 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83
04 19 00 00 c3 48 83 ec 08 e8 0a fa ff ff 48 89 04 24 b8 02 00 00 00 0f
   05 <48> 8b 3c 24 48 89 c2 e8 53 fa ff ff 48 89 d0 48 83 c4 08 48 3d
      01
[  459.393483] RSP: 002b:00007fe45dfe9a60 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
[  459.394610] RAX: ffffffffffffffda RBX: 00007fe45dfea6d4 RCX: 0000000000416211
[  459.395678] RDX: 00007fe45dfe9b0a RSI: 0000000000000002 RDI: 00007fe45dfe9b00
[  459.396758] RBP: 000000000076bf20 R08: 0000000000000000 R09: 000000000000000a
[  459.397930] R10: 0000000000000075 R11: 0000000000000293 R12: 00000000ffffffff
[  459.399022] R13: 0000000000000bd9 R14: 00000000004cdb80 R15: 000000000076bf2c
[  459.400168]
[  459.400430] Allocated by task 20132:
[  459.401038]  kasan_kmalloc+0xbf/0xe0
[  459.401652]  kmem_cache_alloc+0xd5/0x280
[  459.402330]  bdev_alloc_inode+0x18/0x40
[  459.402970]  alloc_inode+0x5f/0x180
[  459.403510]  iget5_locked+0x57/0xd0
[  459.404095]  bdget+0x94/0x4e0
[  459.404607]  bd_acquire+0xfa/0x2c0
[  459.405113]  blkdev_open+0x110/0x290
[  459.405702]  do_dentry_open+0x49e/0x1050
[  459.406340]  path_openat+0x148c/0x3f50
[  459.406926]  do_filp_open+0x1a1/0x280
[  459.407471]  do_sys_open+0x3c3/0x500
[  459.408010]  do_syscall_64+0xc3/0x520
[  459.408572]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  459.409415]
[  459.409679] Freed by task 1262:
[  459.410212]  __kasan_slab_free+0x129/0x170
[  459.410919]  kmem_cache_free+0xb2/0x2a0
[  459.411564]  rcu_process_callbacks+0xbb2/0x2320
[  459.412318]  __do_softirq+0x225/0x8ac

Fix this by delaying bdput() to the end of blkdev_get() which means we
have finished accessing bdev.

Fixes: 77ea887e ("implement in-kernel gendisk events handling")
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NJason Yan <yanaijie@huawei.com>
Tested-by: NSedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDan Carpenter <dan.carpenter@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      2d3a8e2d
  13. 03 6月, 2020 1 次提交
  15. 27 5月, 2020 1 次提交
    • D
      PM: hibernate: Restrict writes to the resume device · ad1e4f74
      由 Domenico Andreoli 提交于 
      Hibernation via snapshot device requires write permission to the swap
block device, the one that more often (but not necessarily) is used to
store the hibernation image.

With this patch, such permissions are granted iff:

 1) snapshot device config option is enabled
 2) swap partition is used as resume device

In other circumstances the swap device is not writable from userspace.

In order to achieve this, every write attempt to a swap device is
checked against the device configured as part of the uswsusp API [0]
using a pointer to the inode struct in memory. If the swap device being
written was not configured for resuming, the write request is denied.

NOTE: this implementation works only for swap block devices, where the
inode configured by swapon (which sets S_SWAPFILE) is the same used
by SNAPSHOT_SET_SWAP_AREA.

In case of swap file, SNAPSHOT_SET_SWAP_AREA indeed receives the inode
of the block device containing the filesystem where the swap file is
located (+ offset in it) which is never passed to swapon and then has
not set S_SWAPFILE.

As result, the swap file itself (as a file) has never an option to be
written from userspace. Instead it remains writable if accessed directly
from the containing block device, which is always writeable from root.

[0] Documentation/power/userland-swsusp.rst

v2:
 - rename is_hibernate_snapshot_dev() to is_hibernate_resume_dev()
 - fix description so to correctly refer to the resume device
Signed-off-by: NDomenico Andreoli <domenico.andreoli@linux.com>
Acked-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      ad1e4f74
  17. 22 5月, 2020 1 次提交
  19. 21 5月, 2020 1 次提交
  21. 13 5月, 2020 1 次提交
  23. 24 4月, 2020 1 次提交
  25. 21 4月, 2020 3 次提交
  27. 20 4月, 2020 1 次提交
    • D
      bdev: Reduce time holding bd_mutex in sync in blkdev_close() · b849dd84
      由 Douglas Anderson 提交于 
      While trying to "dd" to the block device for a USB stick, I
encountered a hung task warning (blocked for > 120 seconds).  I
managed to come up with an easy way to reproduce this on my system
(where /dev/sdb is the block device for my USB stick) with:

  while true; do dd if=/dev/zero of=/dev/sdb bs=4M; done

With my reproduction here are the relevant bits from the hung task
detector:

 INFO: task udevd:294 blocked for more than 122 seconds.
 ...
 udevd           D    0   294      1 0x00400008
 Call trace:
  ...
  mutex_lock_nested+0x40/0x50
  __blkdev_get+0x7c/0x3d4
  blkdev_get+0x118/0x138
  blkdev_open+0x94/0xa8
  do_dentry_open+0x268/0x3a0
  vfs_open+0x34/0x40
  path_openat+0x39c/0xdf4
  do_filp_open+0x90/0x10c
  do_sys_open+0x150/0x3c8
  ...

 ...
 Showing all locks held in the system:
 ...
 1 lock held by dd/2798:
  #0: ffffff814ac1a3b8 (&bdev->bd_mutex){+.+.}, at: __blkdev_put+0x50/0x204
 ...
 dd              D    0  2798   2764 0x00400208
 Call trace:
  ...
  schedule+0x8c/0xbc
  io_schedule+0x1c/0x40
  wait_on_page_bit_common+0x238/0x338
  __lock_page+0x5c/0x68
  write_cache_pages+0x194/0x500
  generic_writepages+0x64/0xa4
  blkdev_writepages+0x24/0x30
  do_writepages+0x48/0xa8
  __filemap_fdatawrite_range+0xac/0xd8
  filemap_write_and_wait+0x30/0x84
  __blkdev_put+0x88/0x204
  blkdev_put+0xc4/0xe4
  blkdev_close+0x28/0x38
  __fput+0xe0/0x238
  ____fput+0x1c/0x28
  task_work_run+0xb0/0xe4
  do_notify_resume+0xfc0/0x14bc
  work_pending+0x8/0x14

The problem appears related to the fact that my USB disk is terribly
slow and that I have a lot of RAM in my system to cache things.
Specifically my writes seem to be happening at ~15 MB/s and I've got
~4 GB of RAM in my system that can be used for buffering.  To write 4
GB of buffer to disk thus takes ~4000 MB / ~15 MB/s = ~267 seconds.

The 267 second number is a problem because in __blkdev_put() we call
sync_blockdev() while holding the bd_mutex.  Any other callers who
want the bd_mutex will be blocked for the whole time.

The problem is made worse because I believe blkdev_put() specifically
tells other tasks (namely udev) to go try to access the device at right
around the same time we're going to hold the mutex for a long time.

Putting some traces around this (after disabling the hung task detector),
I could confirm:
 dd:    437.608600: __blkdev_put() right before sync_blockdev() for sdb
 udevd: 437.623901: blkdev_open() right before blkdev_get() for sdb
 dd:    661.468451: __blkdev_put() right after sync_blockdev() for sdb
 udevd: 663.820426: blkdev_open() right after blkdev_get() for sdb

A simple fix for this is to realize that sync_blockdev() works fine if
you're not holding the mutex.  Also, it's not the end of the world if
you sync a little early (though it can have performance impacts).
Thus we can make a guess that we're going to need to do the sync and
then do it without holding the mutex.  We still do one last sync with
the mutex but it should be much, much faster.

With this, my hung task warnings for my test case are gone.
Signed-off-by: NDouglas Anderson <dianders@chromium.org>
Reviewed-by: NGuenter Roeck <groeck@chromium.org>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      b849dd84
  29. 23 3月, 2020 1 次提交
  31. 18 3月, 2020 1 次提交
  33. 03 12月, 2019 1 次提交
  35. 14 11月, 2019 5 次提交
  37. 03 11月, 2019 2 次提交
  39. 20 8月, 2019 1 次提交
  41. 16 8月, 2019 1 次提交
    • J
      block: remove REQ_NOWAIT_INLINE · 7b6620d7
      由 Jens Axboe 提交于 
      We had a few issues with this code, and there's still a problem around
how we deal with error handling for chained/split bios. For now, just
revert the code and we'll try again with a thoroug solution. This
reverts commits:

e15c2ffa ("block: fix O_DIRECT error handling for bio fragments")
0eb6ddfb ("block: Fix __blkdev_direct_IO() for bio fragments")
6a43074e ("block: properly handle IOCB_NOWAIT for async O_DIRECT IO")
893a1c97 ("blk-mq: allow REQ_NOWAIT to return an error inline")
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      7b6620d7
  43. 08 8月, 2019 2 次提交
    • J
      bdev: Fixup error handling in blkdev_get() · e91455ba
      由 Jan Kara 提交于 
      Commit 89e524c0 ("loop: Fix mount(2) failure due to race with
LOOP_SET_FD") converted blkdev_get() to use the new helpers for
finishing claiming of a block device. However the conversion botched the
error handling in blkdev_get() and thus the bdev has been marked as held
even in case __blkdev_get() returned error. This led to occasional
warnings with block/001 test from blktests like:

kernel: WARNING: CPU: 5 PID: 907 at fs/block_dev.c:1899 __blkdev_put+0x396/0x3a0

Correct the error handling.

CC: stable@vger.kernel.org
Fixes: 89e524c0 ("loop: Fix mount(2) failure due to race with LOOP_SET_FD")
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      e91455ba
    • J
      block: fix O_DIRECT error handling for bio fragments · e15c2ffa
      由 Jens Axboe 提交于 
      0eb6ddfb tried to fix this up, but introduced a use-after-free
of dio. Additionally, we still had an issue with error handling,
as reported by Darrick:

"I noticed a regression in xfs/747 (an unreleased xfstest for the
xfs_scrub media scanning feature) on 5.3-rc3.  I'll condense that down
to a simpler reproducer:

error-test: 0 209 linear 8:48 0
error-test: 209 1 error
error-test: 210 6446894 linear 8:48 210

Basically we have a ~3G /dev/sdd and we set up device mapper to fail IO
for sector 209 and to pass the io to the scsi device everywhere else.

On 5.3-rc3, performing a directio pread of this range with a < 1M buffer
(in other words, a request for fewer than MAX_BIO_PAGES bytes) yields
EIO like you'd expect:

pread64(3, 0x7f880e1c7000, 1048576, 0)  = -1 EIO (Input/output error)
pread: Input/output error
+++ exited with 0 +++

But doing it with a larger buffer succeeds(!):

pread64(3, "XFSB\0\0\20\0\0\0\0\0\0\fL\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1146880, 0) = 1146880
read 1146880/1146880 bytes at offset 0
1 MiB, 1 ops; 0.0009 sec (1.124 GiB/sec and 1052.6316 ops/sec)
+++ exited with 0 +++

(Note that the part of the buffer corresponding to the dm-error area is
uninitialized)

On 5.3-rc2, both commands would fail with EIO like you'd expect.  The
only change between rc2 and rc3 is commit 0eb6ddfb ("block: Fix
__blkdev_direct_IO() for bio fragments").

AFAICT we end up in __blkdev_direct_IO with a 1120K buffer, which gets
split into two bios: one for the first BIO_MAX_PAGES worth of data (1MB)
and a second one for the 96k after that."

Fix this by noting that it's always safe to dereference dio if we get
BLK_QC_T_EAGAIN returned, as end_io hasn't been run for that case. So
we can safely increment the dio size before calling submit_bio(), and
then decrement it on failure (not that it really matters, as the bio
and dio are going away).

For error handling, return to the original method of just using 'ret'
for tracking the error, and the size tracking in dio->size.

Fixes: 0eb6ddfb ("block: Fix __blkdev_direct_IO() for bio fragments")
Fixes: 6a43074e ("block: properly handle IOCB_NOWAIT for async O_DIRECT IO")
Reported-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      e15c2ffa
  45. 02 8月, 2019 1 次提交
    • D
      block: Fix __blkdev_direct_IO() for bio fragments · 0eb6ddfb
      由 Damien Le Moal 提交于 
      The recent fix to properly handle IOCB_NOWAIT for async O_DIRECT IO
(patch 6a43074e) introduced two problems with BIO fragment handling
for direct IOs:
1) The dio size processed is calculated by incrementing the ret variable
by the size of the bio fragment issued for the dio. However, this size
is obtained directly from bio->bi_iter.bi_size AFTER the bio submission
which may result in referencing the bi_size value after the bio
completed, resulting in an incorrect value use.
2) The ret variable is not incremented by the size of the last bio
fragment issued for the bio, leading to an invalid IO size being
returned to the user.

Fix both problem by using dio->size (which is incremented before the bio
submission) to update the value of ret after bio submissions, including
for the last bio fragment issued.

Fixes: 6a43074e ("block: properly handle IOCB_NOWAIT for async O_DIRECT IO")
Reported-by: NMasato Suzuki <masato.suzuki@wdc.com>
Signed-off-by: NDamien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      0eb6ddfb
  47. 31 7月, 2019 1 次提交
    • J
      loop: Fix mount(2) failure due to race with LOOP_SET_FD · 89e524c0
      由 Jan Kara 提交于 
      Commit 33ec3e53 ("loop: Don't change loop device under exclusive
opener") made LOOP_SET_FD ioctl acquire exclusive block device reference
while it updates loop device binding. However this can make perfectly
valid mount(2) fail with EBUSY due to racing LOOP_SET_FD holding
temporarily the exclusive bdev reference in cases like this:

for i in {a..z}{a..z}; do
        dd if=/dev/zero of=$i.image bs=1k count=0 seek=1024
        mkfs.ext2 $i.image
        mkdir mnt$i
done

echo "Run"
for i in {a..z}{a..z}; do
        mount -o loop -t ext2 $i.image mnt$i &
done

Fix the problem by not getting full exclusive bdev reference in
LOOP_SET_FD but instead just mark the bdev as being claimed while we
update the binding information. This just blocks new exclusive openers
instead of failing them with EBUSY thus fixing the problem.

Fixes: 33ec3e53 ("loop: Don't change loop device under exclusive opener")
Cc: stable@vger.kernel.org
Tested-by: NKai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      89e524c0
  49. 22 7月, 2019 1 次提交
    • J
      block: properly handle IOCB_NOWAIT for async O_DIRECT IO · 6a43074e
      由 Jens Axboe 提交于 
      A caller is supposed to pass in REQ_NOWAIT if we can't block for any
given operation, but O_DIRECT for block devices just ignore this. Hence
we'll block for various resource shortages on the block layer side,
like having to wait for requests.

Use the new REQ_NOWAIT_INLINE to ask for this error to be returned
inline, so we can handle it appropriately and return -EAGAIN to the
caller.
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      6a43074e
  51. 29 6月, 2019 2 次提交