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drm/i915/display: check configuration index before shifting

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The calc_allowed_config_filter() function passes the return value of
iter_pos_to_idx() directly to BIT(), but the helper can return -1 for
an invalid iterator.

The iterator already rejects negative indices before doing a
configuration, so this should not matter in normal flows.  In any
case, for robustness, check the index explicitly and warn if it is
negative, avoiding an undefined shift.

Fixes: 39e30bdf2f ("drm/i915/dp_link_caps: Add link configuration iterator")
Reviewed-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260908100659.113555-1-luciano.coelho@intel.com
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
(cherry picked from commit fe05cb9b9fb0ecc10409c4c6133257214b6cd8c8)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Luca Coelho 2026-09-08 13:06:51 +03:00 committed by Jani Nikula
parent fd73f4a665
commit ee415ce8cb
1 changed files with 8 additions and 1 deletions
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9
drivers/gpu/drm/i915/display/intel_dp_link_caps.c
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@ -426,12 +426,15 @@ calc_allowed_config_filter(struct intel_dp_link_caps *link_caps,
const struct intel_dp_link_config *forced_params)
{
struct intel_dp_link_caps_filter allowed_configs = INTEL_DP_LINK_CAPS_FILTER_NONE;
struct intel_display *display = to_intel_display(link_caps->dp);
struct intel_dp_link_caps_order order = bw_desc_config_order();
struct intel_dp_link_caps_iter iter;
struct intel_dp_link_config config;
iter_start(&iter, link_caps, order, enabled_configs);
for_each_dp_link_config(&iter, &config) {
int config_idx;
if (forced_params->rate &&
forced_params->rate != config.rate)
continue;
@ -446,7 +449,11 @@ calc_allowed_config_filter(struct intel_dp_link_caps *link_caps,
if (config.lane_count > max_limits->lane_count)
continue;
allowed_configs.config_mask |= BIT(iter_pos_to_idx(link_caps, order, iter.pos));
config_idx = iter_pos_to_idx(link_caps, order, iter.pos);
if (drm_WARN_ON(display->drm, config_idx < 0))
continue;
allowed_configs.config_mask |= BIT(config_idx);
}
intel_dp_link_caps_iter_end(&iter);