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Stefan Hajnoczi 3c11fec815 virtio-blk: handle block_device_operations callbacks after hot unplug 
[ Upstream commit 90b5feb8c4 ]

A userspace process holding a file descriptor to a virtio_blk device can
still invoke block_device_operations after hot unplug.  This leads to a
use-after-free accessing vblk->vdev in virtblk_getgeo() when
ioctl(HDIO_GETGEO) is invoked:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000090
  IP: [<ffffffffc00e5450>] virtio_check_driver_offered_feature+0x10/0x90 [virtio]
  PGD 800000003a92f067 PUD 3a930067 PMD 0
  Oops: 0000 [#1] SMP
  CPU: 0 PID: 1310 Comm: hdio-getgeo Tainted: G           OE  ------------   3.10.0-1062.el7.x86_64 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  task: ffff9be5fbfb8000 ti: ffff9be5fa890000 task.ti: ffff9be5fa890000
  RIP: 0010:[<ffffffffc00e5450>]  [<ffffffffc00e5450>] virtio_check_driver_offered_feature+0x10/0x90 [virtio]
  RSP: 0018:ffff9be5fa893dc8  EFLAGS: 00010246
  RAX: ffff9be5fc3f3400 RBX: ffff9be5fa893e30 RCX: 0000000000000000
  RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff9be5fbc10b40
  RBP: ffff9be5fa893dc8 R08: 0000000000000301 R09: 0000000000000301
  R10: 0000000000000000 R11: 0000000000000000 R12: ffff9be5fdc24680
  R13: ffff9be5fbc10b40 R14: ffff9be5fbc10480 R15: 0000000000000000
  FS:  00007f1bfb968740(0000) GS:ffff9be5ffc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000090 CR3: 000000003a894000 CR4: 0000000000360ff0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   [<ffffffffc016ac37>] virtblk_getgeo+0x47/0x110 [virtio_blk]
   [<ffffffff8d3f200d>] ? handle_mm_fault+0x39d/0x9b0
   [<ffffffff8d561265>] blkdev_ioctl+0x1f5/0xa20
   [<ffffffff8d488771>] block_ioctl+0x41/0x50
   [<ffffffff8d45d9e0>] do_vfs_ioctl+0x3a0/0x5a0
   [<ffffffff8d45dc81>] SyS_ioctl+0xa1/0xc0

A related problem is that virtblk_remove() leaks the vd_index_ida index
when something still holds a reference to vblk->disk during hot unplug.
This causes virtio-blk device names to be lost (vda, vdb, etc).

Fix these issues by protecting vblk->vdev with a mutex and reference
counting vblk so the vd_index_ida index can be removed in all cases.

Fixes: 48e4043d45 ("virtio: add virtio disk geometry feature")
Reported-by: Lance Digby <ldigby@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Link: https://lore.kernel.org/r/20200430140442.171016-1-stefanha@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-05-20 08:18:33 +02:00
arch x86/unwind/orc: Fix premature unwind stoppage due to IRET frames 2020-05-14 07:57:23 +02:00
block block, bfq: fix use-after-free in bfq_idle_slice_timer_body 2020-04-17 10:48:42 +02:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: api - Fix race condition in crypto_spawn_alg 2020-02-11 04:34:05 -08:00
Documentation arm64: errata: Hide CTR_EL0.DIC on systems affected by Neoverse-N1 #1542419 2020-04-29 16:31:08 +02:00
drivers virtio-blk: handle block_device_operations callbacks after hot unplug 2020-05-20 08:18:33 +02:00
firmware Fix built-in early-load Intel microcode alignment 2020-01-23 08:21:29 +01:00
fs coredump: fix crash when umh is disabled 2020-05-14 07:57:21 +02:00
include net: stricter validation of untrusted gso packets 2020-05-14 07:57:19 +02:00
init fork: fix some -Wmissing-prototypes warnings 2019-12-05 09:21:04 +01:00
ipc ipc/mqueue.c: change __do_notify() to bypass check_kill_permission() 2020-05-14 07:57:23 +02:00
kernel coredump: fix crash when umh is disabled 2020-05-14 07:57:21 +02:00
lib lib: devres: add a helper function for ioremap_uc 2020-05-10 10:30:11 +02:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm shmem: fix possible deadlocks on shmlock_user_lock 2020-05-20 08:18:32 +02:00
net drop_monitor: work around gcc-10 stringop-overflow warning 2020-05-20 08:18:33 +02:00
samples vmalloc: fix remap_vmalloc_range() bounds checks 2020-04-29 16:31:27 +02:00
scripts scripts/decodecode: fix trapping instruction formatting 2020-05-14 07:57:23 +02:00
security selinux: properly handle multiple messages in selinux_netlink_send() 2020-05-06 08:13:32 +02:00
sound ALSA: hda: Match both PCI ID and SSID for driver blacklist 2020-05-10 10:30:12 +02:00
tools objtool: Fix stack offset tracking for indirect CFAs 2020-05-14 07:57:23 +02:00
usr initramfs: restore default compression behavior 2020-04-13 10:44:59 +02:00
virt KVM: arm64: Fix 32bit PC wrap-around 2020-05-14 07:57:20 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.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 updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 16:38:49 +01:00
Makefile Linux 4.19.123 2020-05-14 07:57:23 +02:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.