Bug 2493717 (CVE-2026-53285)

Summary: CVE-2026-53285 kernel: drm/amd/display: Wrap DCN32 phantom-plane allocation in DC_RUN_WITH_PREEMPTION_ENABLED
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's `drm/amd/display` component. When the `dcn32_enable_phantom_plane()` function attempts to allocate memory using `kvzalloc()` within a floating-point unit (FPU) enabled region where software interrupts (softirqs) are disabled, it can trigger an error. This can lead to a kernel crash, resulting in a denial of service (DoS) for the system.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-06-26 21:02:47 UTC 
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)
Comment 1 Mauro Matteo Cascella 2026-06-29 10:02:51 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062615-CVE-2026-53285-c33f@gregkh/T