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UBSAN: invalid-load in amdgpu_dm.c for type '_Bool'

Brief summary of the problem:

I compiled my kernel with UBSAN enabled (UBSAN, UBSAN_BOUNDS, UBSAN_SHIFT, UBSAN_DIV_ZERO, UBSAN_BOOL, UBSAN_ENUM, UBSAN_SANITIZE_ALL) and upon booting with that kernel, I get a warning:

================================================================================
UBSAN: invalid-load in drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:5860:84
load of value 128 is not a valid value for type '_Bool'
CPU: 2 PID: 1 Comm: swapper/0 Tainted: G                T 5.14.17-gentoo-c #3
Hardware name: LENOVO 20UDS0DK00/20UDS0DK00, BIOS R1BET65W(1.34 ) 06/17/2021
Call Trace:
 dump_stack_lvl+0x34/0x44
 ubsan_epilogue+0x5/0x40
 __ubsan_handle_load_invalid_value.cold+0x43/0x48
 create_stream_for_sink.cold+0x3a/0x7d
 create_validate_stream_for_sink+0x50/0x140
 amdgpu_dm_connector_mode_valid+0x4a/0x180
 drm_connector_mode_valid+0x30/0x50
 drm_helper_probe_single_connector_modes+0x3af/0x870
 drm_client_modeset_probe+0x22c/0x5d0
 ? drm_file_alloc+0x1ac/0x250
 __drm_fb_helper_initial_config_and_unlock+0x2b/0xc0
 amdgpu_fbdev_init+0xc3/0x100
 amdgpu_device_init.cold+0x2ed/0x74e
 amdgpu_driver_load_kms+0x45/0x260
 amdgpu_pci_probe+0xda/0x160
 pci_device_probe+0x9e/0x110
 really_probe.part.0+0xb3/0x290
 __driver_probe_device+0xa9/0x150
 driver_probe_device+0x19/0x100
 __driver_attach+0xbc/0x1a0
 ? __device_attach_driver+0x120/0x120
 bus_for_each_dev+0x73/0xb0
 bus_add_driver+0x106/0x1c0
 driver_register+0x8a/0xe0
 ? drm_sched_fence_slab_init+0x80/0x80
 do_one_initcall+0x3f/0x1c0
 do_initcalls+0x1d3/0x22f
 kernel_init_freeable+0x159/0x1bc
 ? rest_init+0xe0/0xe0
 kernel_init+0x12/0x130
 ? rest_init+0xe0/0xe0
 ret_from_fork+0x22/0x30
================================================================================

In the end the boot fails, as I don't reach my desktop environment.

Hardware description:

  • CPU: Ryzen 4750U
  • GPU: Advanced Micro Devices, Inc. [AMD/ATI] Renoir [1002:1636] (rev d1)
  • System Memory: 48 GiB
  • Display(s): 2 connected, 1 active
  • Type of Display Connection: laptop, external DP via USB-C dock

System information:

  • Distro name and Version: Gentoo
  • Kernel version: 5.14.17
  • Custom kernel: gentoo patches (very light, almost upstream)
  • AMD official driver version: 19.1.0

How to reproduce the issue:

  • Activate UBSAN in the kernel-config (UBSAN, UBSAN_BOUNDS, UBSAN_SHIFT, UBSAN_DIV_ZERO, UBSAN_BOOL, UBSAN_ENUM, UBSAN_SANITIZE_ALL)
  • Recompile kernel
  • Install modules
  • Install kernel to /boot
  • boot with UBSAN-enabled kernel

Other reports

I've seen one possibly related bug report on the kernel Bugzilla.