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

Summary

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)

Timeline

1. Jun 26, 2026, 7:40 PM UTCCVE published
2. Oct 21, 2026, 12:42 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 235c67634230b0f9ad8c0185272fed36c892b1c4 · fixed in 19e82047cb68bcde55791ee20178acd431609b8d; From 235c67634230b0f9ad8c0185272fed36c892b1c4 · fixed in a8c1480bb066cf0f6e79129b7292e1c99ff68b9b; From 235c67634230b0f9ad8c0185272fed36c892b1c4 · fixed in 30bb2ec6695d62f63db4aa6179c4626834ed0cd6; From 235c67634230b0f9ad8c0185272fed36c892b1c4 · fixed in 183182235f6d53bac62c6c39014738a54a68dfa6

• Linux Linux

  6.0

• KernelLinux

  From 6.0.0 · fixed in 6.12.114; From 6.13.0 · fixed in 6.18.57; From 6.19.0 · fixed in 7.0.10

References 4