CVE-2026-53285 — drm/amd/display: Wrap DCN32 phantom-plane allocation in DC_RUN_WITH_PREEMPTION_ENABLED

Affected: Linux

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

drm/amd/display: Wrap DCN32 phantom-plane allocation in DC_RUN_WITH_PREEMPTION_ENABLED

[Why] dcn32_validate_bandwidth() wraps dcn32_internal_validate_bw() with DC_FP_START()/DC_FP_END(). In x86 non-RT, DC_FP_START takes fpregs_lock(), which disables local softirqs.

The DML1 path through dcn32_enable_phantom_plane() calls kvzalloc() to allocate ~335 KiB for dc_plane_state. This triggers the vmalloc path, which calls BUG_ON(in_interrupt()) because it's invoked within the FPU-enabled (softirq disabled) region, leading to a kernel crash.

[How] Wrap the dc_state_create_phantom_plane() call with the DC_RUN_WITH_PREEMPTION_ENABLED() macro to allow preemption during this memory allocation.

(cherry picked from commit 885ccbef7b94a8b38f69c4211c679021aa27ad11)

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CVE-2026-53285 — drm/amd/display: Wrap DCN32 phantom-plane allocation in DC_RUN_WITH_PREEMPTION_ENABLED