linux.git/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_hdcp.c, branch v6.15

drm/amd/display: Fix slab-use-after-free in hdcp

2025-05-01T15:01:23+00:00

The HDCP code in amdgpu_dm_hdcp.c copies pointers to amdgpu_dm_connector
objects without incrementing the kref reference counts. When using a
USB-C dock, and the dock is unplugged, the corresponding
amdgpu_dm_connector objects are freed, creating dangling pointers in the
HDCP code. When the dock is plugged back, the dangling pointers are
dereferenced, resulting in a slab-use-after-free:

[   66.775837] BUG: KASAN: slab-use-after-free in event_property_validate+0x42f/0x6c0 [amdgpu]
[   66.776171] Read of size 4 at addr ffff888127804120 by task kworker/0:1/10

[   66.776179] CPU: 0 UID: 0 PID: 10 Comm: kworker/0:1 Not tainted 6.14.0-rc7-00180-g54505f727a38-dirty #233
[   66.776183] Hardware name: HP HP Pavilion Aero Laptop 13-be0xxx/8916, BIOS F.17 12/18/2024
[   66.776186] Workqueue: events event_property_validate [amdgpu]
[   66.776494] Call Trace:
[   66.776496]  
[   66.776497]  dump_stack_lvl+0x70/0xa0
[   66.776504]  print_report+0x175/0x555
[   66.776507]  ? __virt_addr_valid+0x243/0x450
[   66.776510]  ? kasan_complete_mode_report_info+0x66/0x1c0
[   66.776515]  kasan_report+0xeb/0x1c0
[   66.776518]  ? event_property_validate+0x42f/0x6c0 [amdgpu]
[   66.776819]  ? event_property_validate+0x42f/0x6c0 [amdgpu]
[   66.777121]  __asan_report_load4_noabort+0x14/0x20
[   66.777124]  event_property_validate+0x42f/0x6c0 [amdgpu]
[   66.777342]  ? __lock_acquire+0x6b40/0x6b40
[   66.777347]  ? enable_assr+0x250/0x250 [amdgpu]
[   66.777571]  process_one_work+0x86b/0x1510
[   66.777575]  ? pwq_dec_nr_in_flight+0xcf0/0xcf0
[   66.777578]  ? assign_work+0x16b/0x280
[   66.777580]  ? lock_is_held_type+0xa3/0x130
[   66.777583]  worker_thread+0x5c0/0xfa0
[   66.777587]  ? process_one_work+0x1510/0x1510
[   66.777588]  kthread+0x3a2/0x840
[   66.777591]  ? kthread_is_per_cpu+0xd0/0xd0
[   66.777594]  ? trace_hardirqs_on+0x4f/0x60
[   66.777597]  ? _raw_spin_unlock_irq+0x27/0x60
[   66.777599]  ? calculate_sigpending+0x77/0xa0
[   66.777602]  ? kthread_is_per_cpu+0xd0/0xd0
[   66.777605]  ret_from_fork+0x40/0x90
[   66.777607]  ? kthread_is_per_cpu+0xd0/0xd0
[   66.777609]  ret_from_fork_asm+0x11/0x20
[   66.777614]  

[   66.777643] Allocated by task 10:
[   66.777646]  kasan_save_stack+0x39/0x60
[   66.777649]  kasan_save_track+0x14/0x40
[   66.777652]  kasan_save_alloc_info+0x37/0x50
[   66.777655]  __kasan_kmalloc+0xbb/0xc0
[   66.777658]  __kmalloc_cache_noprof+0x1c8/0x4b0
[   66.777661]  dm_dp_add_mst_connector+0xdd/0x5c0 [amdgpu]
[   66.777880]  drm_dp_mst_port_add_connector+0x47e/0x770 [drm_display_helper]
[   66.777892]  drm_dp_send_link_address+0x1554/0x2bf0 [drm_display_helper]
[   66.777901]  drm_dp_check_and_send_link_address+0x187/0x1f0 [drm_display_helper]
[   66.777909]  drm_dp_mst_link_probe_work+0x2b8/0x410 [drm_display_helper]
[   66.777917]  process_one_work+0x86b/0x1510
[   66.777919]  worker_thread+0x5c0/0xfa0
[   66.777922]  kthread+0x3a2/0x840
[   66.777925]  ret_from_fork+0x40/0x90
[   66.777927]  ret_from_fork_asm+0x11/0x20

[   66.777932] Freed by task 1713:
[   66.777935]  kasan_save_stack+0x39/0x60
[   66.777938]  kasan_save_track+0x14/0x40
[   66.777940]  kasan_save_free_info+0x3b/0x60
[   66.777944]  __kasan_slab_free+0x52/0x70
[   66.777946]  kfree+0x13f/0x4b0
[   66.777949]  dm_dp_mst_connector_destroy+0xfa/0x150 [amdgpu]
[   66.778179]  drm_connector_free+0x7d/0xb0
[   66.778184]  drm_mode_object_put.part.0+0xee/0x160
[   66.778188]  drm_mode_object_put+0x37/0x50
[   66.778191]  drm_atomic_state_default_clear+0x220/0xd60
[   66.778194]  __drm_atomic_state_free+0x16e/0x2a0
[   66.778197]  drm_mode_atomic_ioctl+0x15ed/0x2ba0
[   66.778200]  drm_ioctl_kernel+0x17a/0x310
[   66.778203]  drm_ioctl+0x584/0xd10
[   66.778206]  amdgpu_drm_ioctl+0xd2/0x1c0 [amdgpu]
[   66.778375]  __x64_sys_ioctl+0x139/0x1a0
[   66.778378]  x64_sys_call+0xee7/0xfb0
[   66.778381]  do_syscall_64+0x87/0x140
[   66.778385]  entry_SYSCALL_64_after_hwframe+0x4b/0x53

Fix this by properly incrementing and decrementing the reference counts
when making and deleting copies of the amdgpu_dm_connector pointers.

(Mario: rebase on current code and update fixes tag)

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4006
Signed-off-by: Chris Bainbridge 
Fixes: da3fd7ac0bcf3 ("drm/amd/display: Update CP property based on HW query")
Reviewed-by: Alex Hung 
Link: https://lore.kernel.org/r/20250417215005.37964-1-mario.limonciello@amd.com
Signed-off-by: Mario Limonciello 
Signed-off-by: Alex Deucher 
(cherry picked from commit d4673f3c3b3dcb74e36e53cdfc880baa7a87b330)
Cc: stable@vger.kernel.org

Merge tag 'driver-core-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2025-04-01T18:02:03+00:00

Pull driver core updatesk from Greg KH:
 "Here is the big set of driver core updates for 6.15-rc1. Lots of stuff
  happened this development cycle, including:

   - kernfs scaling changes to make it even faster thanks to rcu

   - bin_attribute constify work in many subsystems

   - faux bus minor tweaks for the rust bindings

   - rust binding updates for driver core, pci, and platform busses,
     making more functionaliy available to rust drivers. These are all
     due to people actually trying to use the bindings that were in
     6.14.

   - make Rafael and Danilo full co-maintainers of the driver core
     codebase

   - other minor fixes and updates"

* tag 'driver-core-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (52 commits)
  rust: platform: require Send for Driver trait implementers
  rust: pci: require Send for Driver trait implementers
  rust: platform: impl Send + Sync for platform::Device
  rust: pci: impl Send + Sync for pci::Device
  rust: platform: fix unrestricted &mut platform::Device
  rust: pci: fix unrestricted &mut pci::Device
  rust: device: implement device context marker
  rust: pci: use to_result() in enable_device_mem()
  MAINTAINERS: driver core: mark Rafael and Danilo as co-maintainers
  rust/kernel/faux: mark Registration methods inline
  driver core: faux: only create the device if probe() succeeds
  rust/faux: Add missing parent argument to Registration::new()
  rust/faux: Drop #[repr(transparent)] from faux::Registration
  rust: io: fix devres test with new io accessor functions
  rust: io: rename `io::Io` accessors
  kernfs: Move dput() outside of the RCU section.
  efi: rci2: mark bin_attribute as __ro_after_init
  rapidio: constify 'struct bin_attribute'
  firmware: qemu_fw_cfg: constify 'struct bin_attribute'
  powerpc/perf/hv-24x7: Constify 'struct bin_attribute'
  ...

drm/amd/display: Drop unnecessary ret variable for enable_assr()

2025-03-10T17:35:49+00:00

[Why]
enable_assr() has a res variable that only is changed in one block with
no cleanup necessary.

[How]
Remove variable and return early from failure cases.

Reviewed-by: Alex Hung 
Signed-off-by: Mario Limonciello 
Signed-off-by: Tom Chung 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher

drm/amd/display: Add scoped mutexes for amdgpu_dm_dhcp

2025-03-10T17:32:58+00:00

[Why]
Guards automatically release mutex when it goes out of scope making
code easier to follow.

[How]
Replace all use of mutex_lock()/mutex_unlock() with guard(mutex).

Reviewed-by: Alex Hung 
Signed-off-by: Mario Limonciello 
Signed-off-by: Tom Chung 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher

drm/amd/display: Fix slab-use-after-free on hdcp_work

2025-03-10T17:30:51+00:00

[Why]
A slab-use-after-free is reported when HDCP is destroyed but the
property_validate_dwork queue is still running.

[How]
Cancel the delayed work when destroying workqueue.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4006
Fixes: da3fd7ac0bcf ("drm/amd/display: Update CP property based on HW query")
Cc: Alex Deucher 
Reviewed-by: Alex Hung 
Signed-off-by: Mario Limonciello 
Signed-off-by: Tom Chung 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher

drm/amd/display: Constify 'struct bin_attribute'

2025-02-21T08:20:31+00:00

The sysfs core now allows instances of 'struct bin_attribute' to be
moved into read-only memory. Make use of that to protect them against
accidental or malicious modifications.

Signed-off-by: Thomas Weißschuh 
Reviewed-by: Harry Wentland 
Link: https://lore.kernel.org/r/20241216-sysfs-const-bin_attr-drm-v1-5-210f2b36b9bf@weissschuh.net
Signed-off-by: Greg Kroah-Hartman

drm/amd/display: Support DCN36 HDCP

2025-02-13T02:04:08+00:00

Add case in hdcp_create_workqueue() to support HDCP on DCN36 as well.

Acked-by: Harry Wentland 
Signed-off-by: Wayne Lin 
Signed-off-by: Alex Deucher

drm/amd/display: add amdgpu_dm support for DCN351

2024-03-04T20:59:08+00:00

Add Display Manager specific changes for DCN3.5.1.

Signed-off-by: Hamza Mahfooz 
Signed-off-by: Alex Deucher

drm/amd/display: Add DCN35 DM Support

2023-08-30T19:51:16+00:00

[Why & How]
Add DM handling for DCN35.

Signed-off-by: Qingqing Zhuo 
Acked-by: Harry Wentland 
Signed-off-by: Alex Deucher

drm/amd/display: Change HDCP update sequence for DM

2023-08-07T21:14:09+00:00

Refactor the sequence in hdcp_update_display() to use
mod_hdcp_update_display().

Previous sequence:
	- remove()->add()

This Sequence was used to update the display, (mod_hdcp_update_display
didn't exist at the time). This meant for any hdcp updates (type changes,
enable/disable) we would remove, reconstruct, and add. This leads to
unnecessary calls to psp eventually

New Sequence using mod_hdcp_update_display():
	- add() once when stream is enabled
	- use update() for all updates

The update function checks for prev == new states and will not
unnecessarily end up calling psp via add/remove.

Reviewed-by: Qingqing Zhuo 
Acked-by: Tom Chung 
Signed-off-by: Bhawanpreet Lakha 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher