drm/amd/display: Fix out-of-bounds read in dp_get_eq_aux_rd_interval()

Overview

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

drm/amd/display: Fix out-of-bounds read in dp_get_eq_aux_rd_interval()

[Why & How] The aux_rd_interval array in struct dc_lttpr_caps is declared with MAX_REPEATER_CNT - 1 (7) elements, indexed 0..6. However, the offset parameter passed to dp_get_eq_aux_rd_interval() can be as large as MAX_REPEATER_CNT (8) when a sink reports 8 LTTPR repeaters via DPCD. This leads to an out-of-bounds read of aux_rd_interval[7] when offset is 8.

Fix this by growing aux_rd_interval to MAX_REPEATER_CNT elements to accommodate the full range of valid repeater counts defined by the DP spec.

(cherry picked from commit a55a458a8df37a65ffda5cf721d554a8f74f6b04)

Affected

• Linux >= 8e5100a575433cc185a2e224280fbd873b6692dd < a632474c793b7f2a9bbd3d8e3d0dd7d256989300
• Linux >= 8e5100a575433cc185a2e224280fbd873b6692dd < 7c5f2d16a8f4464bf2a719ceb2316b8a6b87a3c0
• Linux >= 8e5100a575433cc185a2e224280fbd873b6692dd < 454d3b3d499c18373f8960d31aea48338a3ca9e0
• Linux >= 8e5100a575433cc185a2e224280fbd873b6692dd < dc1490927d79fe9621e29f4a4f5d7b5ccb6aea3e
• Linux >= 8e5100a575433cc185a2e224280fbd873b6692dd < e8b4d37eba05141ee01794fc6b7f2da808cee83b
• Linux 5.6

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.