linux-stable.git/drivers/gpu/drm/drm_auth.c, branch linux-4.9.y

drm: Lock pointer access in drm_master_release()

2021-06-16T09:36:34+00:00

commit c336a5ee984708db4826ef9e47d184e638e29717 upstream.

This patch eliminates the following smatch warning:
drivers/gpu/drm/drm_auth.c:320 drm_master_release() warn: unlocked access 'master' (line 318) expected lock '&dev->master_mutex'

The 'file_priv->master' field should be protected by the mutex lock to
'&dev->master_mutex'. This is because other processes can concurrently
modify this field and free the current 'file_priv->master'
pointer. This could result in a use-after-free error when 'master' is
dereferenced in subsequent function calls to
'drm_legacy_lock_master_cleanup()' or to 'drm_lease_revoke()'.

An example of a scenario that would produce this error can be seen
from a similar bug in 'drm_getunique()' that was reported by Syzbot:
https://syzkaller.appspot.com/bug?id=148d2f1dfac64af52ffd27b661981a540724f803

In the Syzbot report, another process concurrently acquired the
device's master mutex in 'drm_setmaster_ioctl()', then overwrote
'fpriv->master' in 'drm_new_set_master()'. The old value of
'fpriv->master' was subsequently freed before the mutex was unlocked.

Reported-by: Dan Carpenter 
Signed-off-by: Desmond Cheong Zhi Xi 
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter 
Link: https://patchwork.freedesktop.org/patch/msgid/20210609092119.173590-1-desmondcheongzx@gmail.com
Signed-off-by: Greg Kroah-Hartman

drm: set is_master to 0 upon drm_new_set_master() failure

2018-12-08T12:05:06+00:00

commit 23a336b34258aba3b50ea6863cca4e81b5ef6384 upstream.

When drm_new_set_master() fails, set is_master to 0, to prevent a
possible NULL pointer deref.

Here is a problematic flow: we check is_master in drm_is_current_master(),
then proceed to call drm_lease_owner() passing master. If we do not restore
is_master status when drm_new_set_master() fails, we may have a situation
in which is_master will be 1 and master itself, NULL, leading to the deref
of a NULL pointer in drm_lease_owner().

This fixes the following OOPS, observed on an ArchLinux running a 4.19.2
kernel:

[   97.804282] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
[   97.807224] PGD 0 P4D 0
[   97.807224] Oops: 0000 [#1] PREEMPT SMP NOPTI
[   97.807224] CPU: 0 PID: 1348 Comm: xfwm4 Tainted: P           OE     4.19.2-arch1-1-ARCH #1
[   97.807224] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./AB350 Pro4, BIOS P5.10 10/16/2018
[   97.807224] RIP: 0010:drm_lease_owner+0xd/0x20 [drm]
[   97.807224] Code: 83 c4 18 5b 5d c3 b8 ea ff ff ff eb e2 b8 ed ff ff ff eb db e8 b4 ca 68 fb 0f 1f 40 00 0f 1f 44 00 00 48 89 f8 eb 03 48 89 d0 <48> 8b 90 80 00 00 00 48 85 d2 75 f1 c3 66 0f 1f 44 00 00 0f 1f 44
[   97.807224] RSP: 0018:ffffb8cf08e07bb0 EFLAGS: 00010202
[   97.807224] RAX: 0000000000000000 RBX: ffff9cf0f2586c00 RCX: ffff9cf0f2586c88
[   97.807224] RDX: ffff9cf0ddbd8000 RSI: 0000000000000000 RDI: 0000000000000000
[   97.807224] RBP: ffff9cf1040e9800 R08: 0000000000000000 R09: 0000000000000000
[   97.807224] R10: ffffdeb30fd5d680 R11: ffffdeb30f5d6808 R12: ffff9cf1040e9888
[   97.807224] R13: 0000000000000000 R14: dead000000000200 R15: ffff9cf0f2586cc8
[   97.807224] FS:  00007f4145513180(0000) GS:ffff9cf10ea00000(0000) knlGS:0000000000000000
[   97.807224] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   97.807224] CR2: 0000000000000080 CR3: 00000003d7548000 CR4: 00000000003406f0
[   97.807224] Call Trace:
[   97.807224]  drm_is_current_master+0x1a/0x30 [drm]
[   97.807224]  drm_master_release+0x3e/0x130 [drm]
[   97.807224]  drm_file_free.part.0+0x2be/0x2d0 [drm]
[   97.807224]  drm_open+0x1ba/0x1e0 [drm]
[   97.807224]  drm_stub_open+0xaf/0xe0 [drm]
[   97.807224]  chrdev_open+0xa3/0x1b0
[   97.807224]  ? cdev_put.part.0+0x20/0x20
[   97.807224]  do_dentry_open+0x132/0x340
[   97.807224]  path_openat+0x2d1/0x14e0
[   97.807224]  ? mem_cgroup_commit_charge+0x7a/0x520
[   97.807224]  do_filp_open+0x93/0x100
[   97.807224]  ? __check_object_size+0x102/0x189
[   97.807224]  ? _raw_spin_unlock+0x16/0x30
[   97.807224]  do_sys_open+0x186/0x210
[   97.807224]  do_syscall_64+0x5b/0x170
[   97.807224]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[   97.807224] RIP: 0033:0x7f4147b07976
[   97.807224] Code: 89 54 24 08 e8 7b f4 ff ff 8b 74 24 0c 48 8b 3c 24 41 89 c0 44 8b 54 24 08 b8 01 01 00 00 89 f2 48 89 fe bf 9c ff ff ff 0f 05 <48> 3d 00 f0 ff ff 77 30 44 89 c7 89 44 24 08 e8 a6 f4 ff ff 8b 44
[   97.807224] RSP: 002b:00007ffcced96ca0 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
[   97.807224] RAX: ffffffffffffffda RBX: 00005619d5037f80 RCX: 00007f4147b07976
[   97.807224] RDX: 0000000000000002 RSI: 00005619d46b969c RDI: 00000000ffffff9c
[   98.040039] RBP: 0000000000000024 R08: 0000000000000000 R09: 0000000000000000
[   98.040039] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000024
[   98.040039] R13: 0000000000000012 R14: 00005619d5035950 R15: 0000000000000012
[   98.040039] Modules linked in: nct6775 hwmon_vid algif_skcipher af_alg nls_iso8859_1 nls_cp437 vfat fat uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common arc4 videodev media snd_usb_audio snd_hda_codec_hdmi snd_usbmidi_lib snd_rawmidi snd_seq_device mousedev input_leds iwlmvm mac80211 snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_codec edac_mce_amd kvm_amd snd_hda_core kvm iwlwifi snd_hwdep r8169 wmi_bmof cfg80211 snd_pcm irqbypass snd_timer snd libphy soundcore pinctrl_amd rfkill pcspkr sp5100_tco evdev gpio_amdpt k10temp mac_hid i2c_piix4 wmi pcc_cpufreq acpi_cpufreq vboxnetflt(OE) vboxnetadp(OE) vboxpci(OE) vboxdrv(OE) msr sg crypto_user ip_tables x_tables ext4 crc32c_generic crc16 mbcache jbd2 fscrypto uas usb_storage dm_crypt hid_generic usbhid hid
[   98.040039]  dm_mod raid1 md_mod sd_mod crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel pcbc ahci libahci aesni_intel aes_x86_64 libata crypto_simd cryptd glue_helper ccp xhci_pci rng_core scsi_mod xhci_hcd nvidia_drm(POE) drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm agpgart nvidia_uvm(POE) nvidia_modeset(POE) nvidia(POE) ipmi_devintf ipmi_msghandler
[   98.040039] CR2: 0000000000000080
[   98.040039] ---[ end trace 3b65093b6fe62b2f ]---
[   98.040039] RIP: 0010:drm_lease_owner+0xd/0x20 [drm]
[   98.040039] Code: 83 c4 18 5b 5d c3 b8 ea ff ff ff eb e2 b8 ed ff ff ff eb db e8 b4 ca 68 fb 0f 1f 40 00 0f 1f 44 00 00 48 89 f8 eb 03 48 89 d0 <48> 8b 90 80 00 00 00 48 85 d2 75 f1 c3 66 0f 1f 44 00 00 0f 1f 44
[   98.040039] RSP: 0018:ffffb8cf08e07bb0 EFLAGS: 00010202
[   98.040039] RAX: 0000000000000000 RBX: ffff9cf0f2586c00 RCX: ffff9cf0f2586c88
[   98.040039] RDX: ffff9cf0ddbd8000 RSI: 0000000000000000 RDI: 0000000000000000
[   98.040039] RBP: ffff9cf1040e9800 R08: 0000000000000000 R09: 0000000000000000
[   98.040039] R10: ffffdeb30fd5d680 R11: ffffdeb30f5d6808 R12: ffff9cf1040e9888
[   98.040039] R13: 0000000000000000 R14: dead000000000200 R15: ffff9cf0f2586cc8
[   98.040039] FS:  00007f4145513180(0000) GS:ffff9cf10ea00000(0000) knlGS:0000000000000000
[   98.040039] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   98.040039] CR2: 0000000000000080 CR3: 00000003d7548000 CR4: 00000000003406f0

Signed-off-by: Sergio Correia 
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter 
Link: https://patchwork.freedesktop.org/patch/msgid/20181122053329.2692-1-sergio@correia.cc
Signed-off-by: Sean Paul 
Signed-off-by: Greg Kroah-Hartman

drm: Used DRM_LEGACY for all legacy functions

2016-08-08T08:05:23+00:00

Except for nouveau, only legacy drivers need this really. And nouveau
is already marked up with DRIVER_KMS_LEGACY_CONTEXT as the special
case.

I've tried to be careful to leave everything related to modeset still
using the DRIVER_MODESET flag. Otherwise it's a direct replacement of
!DRIVER_MODESET with DRIVER_LEGACY checks. Also helps readability
since fewer negative checks overall.

Reviewed-by: David Herrmann 
Reviewed-by: Frank Binns 
Signed-off-by: Daniel Vetter 
Link: http://patchwork.freedesktop.org/patch/msgid/1470251470-30830-2-git-send-email-daniel.vetter@ffwll.ch

drm: document drm_auth.c

2016-06-21T20:10:55+00:00

Also extract drm_auth.h for nicer grouping.

v2: Nuke the other comments since they don't really explain a lot, and
within the drm core we generally only document functions exported to
drivers: The main audience for these docs are driver writers.

v3: Limit the exposure of drm_master internals by only including
drm_auth.h where it is neede (Chris).

v4: Spelling polish (Emil).

Cc: Chris Wilson 
Reviewed-by: Chris Wilson 
Reviewed-by: Emil Velikov 
Signed-off-by: Daniel Vetter

drm: Clear up master tracking booleans

2016-06-21T19:58:29+00:00

- is_master can be removed, we can compute this by checking allowed_master
  (which really just tracks whether a master struct has been allocated
  for this fpriv in either open or set_master), and whether the fpriv is
  the current master on the device.

- that frees up is_master as a good replacement name for allowed_master.
  With that it's clear that it tracks whether the fpriv is a master (with
  possibly clients attached to it and authenticated against it), and that
  one of those fprivs with is_master set is the current master.

v2: Fix kerneldoc for is_master (Emil).

Cc: Chris Wilson 
Cc: Thomas Hellstrom 
Reviewed-by: Chris Wilson 
Reviewed-by: Emil Velikov 
Signed-off-by: Daniel Vetter 
Link: http://patchwork.freedesktop.org/patch/msgid/1466499262-18717-10-git-send-email-daniel.vetter@ffwll.ch

drm: Extract drm_is_current_master

2016-06-21T19:58:12+00:00

Just rolling out a bit of abstraction to be able to clean
up the master logic in the next step.

Cc: Chris Wilson 
Cc: Thomas Hellstrom 
Reviewed-by: Chris Wilson 
Reviewed-by: Emil Velikov 
Signed-off-by: Daniel Vetter

drm: Refactor drop/set master code a bit

2016-06-21T19:56:28+00:00

File open/set_maseter ioctl and file close/drop_master ioctl share the
same master handling code. Extract it.

Note that vmwgfx's master_set callback needs to know whether the
master is a new one or has been used already, so thread this through.
On the close/drop side a similar parameter existed, but wasnt used.
Drop it to simplify the flow.

v2: Try to make it not leak so much (Emil).

v3: Send out the right version ...

Cc: Emil Velikov 
Cc: Chris Wilson 
Cc: Thomas Hellstrom 
Reviewed-by: Chris Wilson 
Reviewed-by: Emil Velikov 
Signed-off-by: Daniel Vetter 
Link: http://patchwork.freedesktop.org/patch/msgid/1466511638-9885-1-git-send-email-daniel.vetter@ffwll.ch

drm: Move master pointer from drm_minor to drm_device

2016-06-21T19:43:24+00:00

There can only be one current master, and it's for the overall device.
Render/control minors don't support master-based auth at all.

This simplifies the master logic a lot, at least in my eyes: All these
additional pointer chases are just confusing.

While doing the conversion I spotted some locking fail:
- drm_lock/drm_auth check dev->master without holding the
  master_mutex. This is fallout from

  commit c996fd0b956450563454e7ccc97a82ca31f9d043
  Author: Thomas Hellstrom 
  Date:   Tue Feb 25 19:57:44 2014 +0100

      drm: Protect the master management with a drm_device::master_mutex v3

  but I honestly don't care one bit about those old legacy drivers
  using this.

- debugfs name info should just grab master_mutex.

- And the fbdev helper looked at it to figure out whether someone is
  using KMS. We just need a consistent value, so READ_ONCE. Aside: We
  should probably check if anyone has opened a control node too, but I
  guess current userspace doesn't really do that yet.

v2: Balance locking, reported by Julia.

v3: Rebase on top of Chris' oops fixes.

Cc: Julia Lawall 
Cc: Chris Wilson 
Reviewed-by: Chris Wilson  (v2)
Reviewed-by: Emil Velikov  (v2)
Signed-off-by: Daniel Vetter 
Link: http://patchwork.freedesktop.org/patch/msgid/1466499262-18717-1-git-send-email-daniel.vetter@ffwll.ch

drm: Protect authmagic with master_mutex

2016-06-20T20:02:09+00:00

Simplifies cleanup, and there's no reason drivers should ever care
about authmagic at all - it's all handled in the core.

And with that, Ladies and Gentlemen, it's time to pop the champagen
and celebrate: dev->struct_mutex is now officially gone from modern
drivers, and if a driver is using gem_free_object_unlocked and doesn't
do anything else silly it's positively impossible to ever touch
dev->struct_mutex at runtime, anywhere.

Well except for the mutex_init on driver load ;-)

v2: Rebased.

Cc: Chris Wilson  (v1)
Reviewed-by: Chris Wilson  (v1)
Reviewed-by: Emil Velikov 
Signed-off-by: Daniel Vetter 
Link: http://patchwork.freedesktop.org/patch/msgid/1466148814-8194-4-git-send-email-daniel.vetter@ffwll.ch

drm: Move authmagic cleanup into drm_master_release

2016-06-20T20:02:01+00:00

It's related, and soon authmagic will also use the master_mutex.

There is an ever-so-slightly semantic change here:
- authmagic will only be cleaned up for primary_client drm_minors. But
  it's impossible to create authmagic on render/control nodes, so this
  is fine.
- The cleanup is moved down a bit in the release processing. Doesn't
  matter at all since authmagic is purely internal logic used by the
  core ioctl access checks, and when we're in a file's release
  callback no one can do ioctls any more.

v2: Rebased.

Cc: Chris Wilson 
Reviewed-by: Chris Wilson  (v1)
Reviewed-by: Emil Velikov 
Signed-off-by: Daniel Vetter 
Link: http://patchwork.freedesktop.org/patch/msgid/1466148814-8194-3-git-send-email-daniel.vetter@ffwll.ch