CVE-2022-49218

In the Linux kernel, the following vulnerability has been resolved:

drm/dp: Fix OOB read when handling Post Cursor2 register

The link_status array was not large enough to read the Adjust Request Post Cursor2 register, so remove the common helper function to avoid an OOB read, found with a -Warray-bounds build:

drivers/gpu/drm/drmdphelper.c: In function 'drmdpgetadjustrequestpostcursor': drivers/gpu/drm/drmdphelper.c:59:27: error: array subscript 10 is outside array bounds of 'const u8[6]' {aka 'const unsigned char[6]'} [-Werror=array-bounds] 59 | return linkstatus[r - DPLANE01STATUS]; | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~ drivers/gpu/drm/drmdphelper.c:147:51: note: while referencing 'linkstatus' 147 | u8 drmdpgetadjustrequestpostcursor(const u8 linkstatus[DPLINKSTATUS_SIZE], | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Replace the only user of the helper with an open-coded fetch and decode, similar to drivers/gpu/drm/amd/display/dc/core/dclinkdp.c.