Linux vulnerability

What happened

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Avoid NULL dereference in dc_dmub_srv error paths In dc_dmub_srv_log_diagnostic_data() and dc_dmub_srv_enable_dpia_trace(). Both functions check: if (!dc_dmub_srv || !dc_dmub_srv->dmub) and then call DC_LOG_ERROR() inside that block. DC_LOG_ERROR() uses dc_dmub_srv->ctx internally. So if dc_dmub_srv is NULL, the logging itself can dereference a NULL pointer and cause a crash. Fix this by splitting the checks. First check if dc_dmub_srv is NULL and return immediately. Then check dc_dmub_srv->dmub and log the error only when dc_dmub_srv is valid. Fixes the below: ../display/dc/dc_dmub_srv.c:962 dc_dmub_srv_log_diagnostic_data() error: we previously assumed 'dc_dmub_srv' could be null (see line 961) ../display/dc/dc_dmub_srv.c:1167 dc_dmub_srv_enable_dpia_trace() error: we previously assumed 'dc_dmub_srv' could be null (see line 1166)

Affected versions

Linux: 2631ac1ac328189031d1aefbbd4929050f72fb23 through before a71fdbd6e8289e2725d33a9873833459f3b1824f (git); 2631ac1ac328189031d1aefbbd4929050f72fb23 through before 2ab18de5ebb11c76bfc8087c5a09fbcccd0dea8a (git); 2631ac1ac328189031d1aefbbd4929050f72fb23 through before b37a978e6d8c33fbfa4abc5dcca4c7cfc6d01f22 (git); 2631ac1ac328189031d1aefbbd4929050f72fb23 through before 4ae3e16f4b3bf64140f773629b765d605ee079a9 (git); 5.14 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.