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Vincent Whitchurch 70ed7148da mic: vop: Fix use-after-free on remove
KASAN detects a use-after-free when vop devices are removed.

This problem was introduced by commit 0063e8bbd2 ("virtio_vop:
don't kfree device on register failure").  That patch moved the freeing
of the struct _vop_vdev to the release function, but failed to ensure
that vop holds a reference to the device when it doesn't want it to go
away.  A kfree() was replaced with a put_device() in the unregistration
path, but the last reference to the device is already dropped in
unregister_virtio_device() so the struct is freed before vop is done
with it.

Fix it by holding a reference until cleanup is done.  This is similar to
the fix in virtio_pci in commit 2989be09a8 ("virtio_pci: fix use
after free on release").

 ==================================================================
 BUG: KASAN: use-after-free in vop_scan_devices+0xc6c/0xe50 [vop]
 Read of size 8 at addr ffff88800da18580 by task kworker/0:1/12

 CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.0.0-rc4+ #53
 Workqueue: events vop_hotplug_devices [vop]
 Call Trace:
  dump_stack+0x74/0xbb
  print_address_description+0x5d/0x2b0
  ? vop_scan_devices+0xc6c/0xe50 [vop]
  kasan_report+0x152/0x1aa
  ? vop_scan_devices+0xc6c/0xe50 [vop]
  ? vop_scan_devices+0xc6c/0xe50 [vop]
  vop_scan_devices+0xc6c/0xe50 [vop]
  ? vop_loopback_free_irq+0x160/0x160 [vop_loopback]
  process_one_work+0x7c0/0x14b0
  ? pwq_dec_nr_in_flight+0x2d0/0x2d0
  ? do_raw_spin_lock+0x120/0x280
  worker_thread+0x8f/0xbf0
  ? __kthread_parkme+0x78/0xf0
  ? process_one_work+0x14b0/0x14b0
  kthread+0x2ae/0x3a0
  ? kthread_park+0x120/0x120
  ret_from_fork+0x3a/0x50

 Allocated by task 12:
  kmem_cache_alloc_trace+0x13a/0x2a0
  vop_scan_devices+0x473/0xe50 [vop]
  process_one_work+0x7c0/0x14b0
  worker_thread+0x8f/0xbf0
  kthread+0x2ae/0x3a0
  ret_from_fork+0x3a/0x50

 Freed by task 12:
  kfree+0x104/0x310
  device_release+0x73/0x1d0
  kobject_put+0x14f/0x420
  unregister_virtio_device+0x32/0x50
  vop_scan_devices+0x19d/0xe50 [vop]
  process_one_work+0x7c0/0x14b0
  worker_thread+0x8f/0xbf0
  kthread+0x2ae/0x3a0
  ret_from_fork+0x3a/0x50

 The buggy address belongs to the object at ffff88800da18008
  which belongs to the cache kmalloc-2k of size 2048
 The buggy address is located 1400 bytes inside of
  2048-byte region [ffff88800da18008, ffff88800da18808)
 The buggy address belongs to the page:
 page:ffffea0000368600 count:1 mapcount:0 mapping:ffff88801440dbc0 index:0x0 compound_mapcount: 0
 flags: 0x4000000000010200(slab|head)
 raw: 4000000000010200 ffffea0000378608 ffffea000037a008 ffff88801440dbc0
 raw: 0000000000000000 00000000000d000d 00000001ffffffff 0000000000000000
 page dumped because: kasan: bad access detected

 Memory state around the buggy address:
  ffff88800da18480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff88800da18500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 >ffff88800da18580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                    ^
  ffff88800da18600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff88800da18680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ==================================================================

Fixes: 0063e8bbd2 ("virtio_vop: don't kfree device on register failure")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-02-01 15:53:18 +01:00
Documentation drm fixes. msm, sun4i, amdgpu, i915 gvt 2019-01-25 12:19:10 +13:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
arch Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-01-27 12:02:00 -08:00
block Revert "block: cover another queue enter recursion via BIO_QUEUE_ENTERED" 2019-01-27 06:35:28 -07:00
certs kbuild: remove redundant target cleaning on failure 2019-01-06 09:46:51 +09:00
crypto crypto: sm3 - fix undefined shift by >= width of value 2019-01-10 21:37:32 +08:00
drivers mic: vop: Fix use-after-free on remove 2019-02-01 15:53:18 +01:00
firmware kbuild: change filechk to surround the given command with { } 2019-01-06 09:46:51 +09:00
fs a set of small smb3 fixes, some fixing various crediting issues discovered during xfstest runs, five for stable 2019-01-26 15:38:22 -08:00
include Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-01-27 11:52:50 -08:00
init kbuild: Disable LD_DEAD_CODE_DATA_ELIMINATION with ftrace & GCC <= 4.7 2019-01-14 10:37:09 +09:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-01-27 11:55:06 -08:00
lib XArray updates for 5.0-rc3 2019-01-22 17:08:30 +13:00
mm for-linus-20190125 2019-01-26 12:42:41 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-27 08:59:12 -08:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-01-30 15:24:45 +01:00
scripts Bug fixes for gcc-plugins 2019-01-21 13:07:03 +13:00
security Merge branch 'fixes-v5.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-01-17 16:54:58 +12:00
sound sound fixes for 5.0-rc4 2019-01-25 05:55:26 +13:00
tools selftests: add binderfs selftests 2019-01-30 15:19:56 +01:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt KVM: validate userspace input in kvm_clear_dirty_log_protect() 2019-01-11 18:38:07 +01:00
.clang-format clang-format: Update .clang-format with the latest for_each macro list 2019-01-19 19:26:06 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support for DT binding schema checks 2018-12-13 09:41:32 -06:00
.mailmap A few early MIPS fixes for 4.21: 2019-01-05 12:48:25 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Add CREDITS entry for Shaohua Li 2019-01-04 14:27:09 -07:00
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-27 08:59:12 -08:00
Makefile Linux 5.0-rc4 2019-01-27 15:18:05 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.