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Filename Latest commit message Latest commit date
Stefan Hajnoczi 645b44b6b3 virtio-blk: handle block_device_operations callbacks after hot unplug
[ Upstream commit 90b5feb8c4bebc76c27fcaf3e1a0e5ca2d319e9e ]

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 08:20:06 +02:00
arch arch/x86/kvm/svm/sev.c: change flag passed to GUP fast in sev_pin_memory() 2020-05-14 07:58:29 +02:00
block iocost: protect iocg->abs_vdebt with iocg->waitq.lock 2020-05-14 07:58:27 +02:00
certs
crypto crypto: rng - Fix a refcounting bug in crypto_rng_reset() 2020-04-17 10:50:16 +02:00
Documentation USB: hub: Revert commit bd0e6c9614 ("usb: hub: try old enumeration scheme first for high speed devices") 2020-04-29 16:33:14 +02:00
drivers virtio-blk: handle block_device_operations callbacks after hot unplug 2020-05-20 08:20:06 +02:00
fs fanotify: merge duplicate events on parent and child 2020-05-14 07:58:30 +02:00
include SUNRPC: Fix GSS privacy computation of auth->au_ralign 2020-05-20 08:20:05 +02:00
init printk: queue wake_up_klogd irq_work only if per-CPU areas are ready 2020-05-02 08:48:42 +02:00
ipc ipc/mqueue.c: change __do_notify() to bypass check_kill_permission() 2020-05-14 07:58:26 +02:00
kernel coredump: fix crash when umh is disabled 2020-05-14 07:58:27 +02:00
lib lib: devres: add a helper function for ioremap_uc 2020-05-10 10:31:30 +02:00
LICENSES
mm shmem: fix possible deadlocks on shmlock_user_lock 2020-05-20 08:20:03 +02:00
net drop_monitor: work around gcc-10 stringop-overflow warning 2020-05-20 08:20:06 +02:00
samples vmalloc: fix remap_vmalloc_range() bounds checks 2020-04-29 16:33:14 +02:00
scripts scripts/decodecode: fix trapping instruction formatting 2020-05-14 07:58:29 +02:00
security selinux: properly handle multiple messages in selinux_netlink_send() 2020-05-06 08:15:17 +02:00
sound ALSA: hda: Match both PCI ID and SSID for driver blacklist 2020-05-10 10:31:31 +02:00
tools ftrace/selftests: workaround cgroup RT scheduling issues 2020-05-20 08:20:05 +02:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: arm: vgic: Synchronize the whole guest on GIC{D,R}_I{S,C}ACTIVER read 2020-05-20 08:20:04 +02:00
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Makefile Linux 5.4.41 2020-05-14 07:58:30 +02:00
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.