CVE-2024-50117

In the Linux kernel, the following vulnerability has been resolved:

drm/amd: Guard against bad data for ATIF ACPI method

If a BIOS provides bad data in response to an ATIF method call

this causes a NULL pointer dereference in the caller.

```

? show_regs (arch/x86/kernel/dumpstack.c:478 (discriminator 1))

? __die (arch/x86/kernel/dumpstack.c:423 arch/x86/kernel/dumpstack.c:434)

? page_fault_oops (arch/x86/mm/fault.c:544 (discriminator 2) arch/x86/mm/fault.c:705 (discriminator 2))

? do_user_addr_fault (arch/x86/mm/fault.c:440 (discriminator 1) arch/x86/mm/fault.c:1232 (discriminator 1))

? acpi_ut_update_object_reference (drivers/acpi/acpica/utdelete.c:642)

? exc_page_fault (arch/x86/mm/fault.c:1542)

? asm_exc_page_fault (./arch/x86/include/asm/idtentry.h:623)

? amdgpu_atif_query_backlight_caps.constprop.0 (drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:387 (discriminator 2)) amdgpu

? amdgpu_atif_query_backlight_caps.constprop.0 (drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:386 (discriminator 1)) amdgpu

```

It has been encountered on at least one system, so guard for it.

(cherry picked from commit c9b7c809b89f24e9372a4e7f02d64c950b07fdee)