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/drm_dp_helper.c: In function drm_dp_get_adjust_request_post_cursor: drivers/gpu/drm/drm_dp_helper.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 link_status[r - DP_LANE0_1_STATUS]; | ^~~~~~~~~~~~ drivers/gpu/drm/drm_dp_helper.c:147:51: note: while referencing link_status 147 | u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE], | ^~~~~~~~~~~~~~~~~~~~~~~

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

Affected Software

References

• https://git.kernel.org/stable/c/a2151490cc6c57b368d7974ffd447a8b36ade639
• https://git.kernel.org/stable/c/aeaed9a9fe694f8b1462fb81e2d33298c929180b