Linux Kernel up to 7.2.9/7.3-rc5 Display Core MST Validation drm/amd/display dm_dp_mst_is_port_support_mode/get_conv_frl_bw dc_sink null pointer dereference

Summaryinfo

A vulnerability categorized as problematic has been discovered in Linux Kernel up to 7.2.9/7.3-rc5. Affected is the function dm_dp_mst_is_port_support_mode/get_conv_frl_bw of the file drm/amd/display of the component Display Core MST Validation. The manipulation of the argument dc_sink results in null pointer dereference. This vulnerability is identified as CVE-2026-98786. The attack is only possible with local access. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.2.9/7.3-rc5. It has been classified as problematic. Affected is the function dm_dp_mst_is_port_support_mode/get_conv_frl_bw of the file drm/amd/display of the component Display Core MST Validation. The manipulation of the argument dc_sink with an unknown input leads to a null pointer dereference vulnerability. CWE is classifying the issue as CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: guard dc_sink dereferences in MST mode validation dm_dp_mst_is_port_support_mode() reads aconnector->dc_sink->dsc_caps... for the DSC branch-throughput check, and get_conv_frl_bw()'s HDMI-PCON FRL-bandwidth path reads aconnector->dc_sink->edid_caps.max_frl_rate, both without a NULL check. dc_sink is cleared asynchronously on MST unplug, and both functions run from paths that the driver's own comments document as racing that teardown: the connector probe worker's ->mode_valid callback and a compositor's atomic check, neither of which holds the MST manager lock that the teardown path uses. The former does have an existing dsc_aux NULL check, but dsc_aux isn't reliably cleared in every path that clears dc_sink, so it doesn't cover this. Fail the port-support check and skip the FRL conversion path when the sink is already gone. (cherry picked from commit 7c3db8da4e039698ae198c870712428644e965c7)

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-98786 since 09/25/2026. The exploitability is told to be easy. Local access is required to approach this attack. Technical details are known, but there is no available exploit.

Upgrading to version 7.2.10 or 7.3-rc6 eliminates this vulnerability. Applying the patch daa0437fe5e451856aaf8fda602a9fc2105bbd54/217f64f348c90cba62164e7ff38e0ccf78a5ca09 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5
• 7.2.6
• 7.2.7
• 7.2.8
• 7.2.9
• 7.3-rc1
• 7.3-rc2
• 7.3-rc3
• 7.3-rc4
• 7.3-rc5

License

• open-source

Website

• Vendor: https://www.kernel.org/

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