Bug 2420246 (CVE-2023-53784)

Summary: CVE-2023-53784 kernel: drm: bridge: dw_hdmi: fix connector access for scdc
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A vulnerability was found in the Linux kernel's DRM subsystem, specifically within the DW HDMI bridge driver .A prior commit intended to improve SCDC (Source Connection Description Channel) debugging changed the interface to retrieve an I2C adapter from a connector structure. However, in the dw_hdmi implementation, the wrong connector pointer was inadvertently used to access the I2C adapter information. This incorrect usage, particularly when the Digital Visual Interface or DisplayPort connector was not properly initialized via the bridge attachment callback, resulting in a NULL pointer dereference.
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Description OSIDB Bzimport 2025-12-09 01:02:58 UTC
In the Linux kernel, the following vulnerability has been resolved:

drm: bridge: dw_hdmi: fix connector access for scdc

Commit 5d844091f237 ("drm/scdc-helper: Pimp SCDC debugs") changed the scdc
interface to pick up an i2c adapter from a connector instead. However, in
the case of dw-hdmi, the wrong connector was being used to pass i2c adapter
information, since dw-hdmi's embedded connector structure is only populated
when the bridge attachment callback explicitly asks for it.

drm-meson is handling connector creation, so this won't happen, leading to
a NULL pointer dereference.

Fix it by having scdc functions access dw-hdmi's current connector pointer
instead, which is assigned during the bridge enablement stage.

[narmstrong: moved Fixes tag before first S-o-b and added Reported-by tag]