CVE-2022-49218: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-49218 affects the Linux kernel's DisplayPort (DP) driver implementation. The vulnerability was discovered in the drmdpgetadjustrequestpostcursor function where an out-of-bounds read could occur when handling the Post Cursor2 register. The issue was identified through a -Warray-bounds build warning, indicating that the link_status array was not large enough to read the Adjust Request Post Cursor2 register (Kernel Git).

The vulnerability stems from an array bounds violation in the drmdpgetadjustrequestpostcursor function within drivers/gpu/drm/drmdphelper.c. The function attempted to access array elements beyond the defined size of the linkstatus array, specifically when accessing linkstatus[r - DPLANE01_STATUS] where the array subscript 10 was outside the bounds of 'const u8[6]' (Kernel Git).

The out-of-bounds read vulnerability could potentially lead to information disclosure or system instability when handling DisplayPort Post Cursor2 register operations (Kernel Git).

The issue has been fixed by removing the common helper function and replacing it with an open-coded fetch and decode implementation, similar to the approach used in drivers/gpu/drm/amd/display/dc/core/dclinkdp.c. The fix involves directly reading the postcursor value from the DPADJUSTREQUESTPOST_CURSOR2 register (Kernel Git).