common/sfc_efx/base: avoid reading past buffer

Existing field ID validity check does not validate the field
descriptor availability. Make it more rigorous to avoid
reading past the buffer containing field descriptors.

Coverity issue: 363742
Fixes: 370ed675a952 ("common/sfc_efx/base: support setting PPORT in match spec")

Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
Reviewed-by: Andy Moreton <amoreton@xilinx.com>

diff --git a/drivers/common/sfc_efx/base/efx_mae.c b/drivers/common/sfc_efx/base/efx_mae.c
index af9a518..ee0a3d3 100644 (file)
--- a/drivers/common/sfc_efx/base/efx_mae.c
+++ b/drivers/common/sfc_efx/base/efx_mae.c
@@ -622,25 +622,30 @@ efx_mae_match_spec_field_set(
        __in_bcount(mask_size)          const uint8_t *mask)
 {
        const efx_mae_mv_desc_t *descp;
+       unsigned int desc_set_nentries;
        uint8_t *mvp;
        efx_rc_t rc;
 
-       if (field_id >= EFX_MAE_FIELD_NIDS) {
-               rc = EINVAL;
-               goto fail1;
-       }
-
        switch (spec->emms_type) {
        case EFX_MAE_RULE_OUTER:
+               desc_set_nentries =
+                   EFX_ARRAY_SIZE(__efx_mae_outer_rule_mv_desc_set);
                descp = &__efx_mae_outer_rule_mv_desc_set[field_id];
                mvp = spec->emms_mask_value_pairs.outer;
                break;
        case EFX_MAE_RULE_ACTION:
+               desc_set_nentries =
+                   EFX_ARRAY_SIZE(__efx_mae_action_rule_mv_desc_set);
                descp = &__efx_mae_action_rule_mv_desc_set[field_id];
                mvp = spec->emms_mask_value_pairs.action;
                break;
        default:
                rc = ENOTSUP;
+               goto fail1;
+       }
+
+       if (field_id >= desc_set_nentries) {
+               rc = EINVAL;
                goto fail2;
        }