server keystore: evict uncommitted slots as a last resort

Author: aidangarske

src/wh_server_keystore.c

@@ -317,6 +317,25 @@ static int _GetKeyCacheSlot(whKeyCacheContext* ctx, uint16_t keySz,
             }
         }
 
+        /* Last-resort fallback: every slot is occupied by an uncommitted
+         * key (typical when many ephemeral keys are cached in succession
+         * with no intervening commit). Reclaim the first non-erased slot
+         * so the cache cannot saturate on transient state alone. Drops
+         * the slot's in-flight contents; the caller's request gets the
+         * slot fresh. */
+        if (foundIndex == -1) {
+            for (i = 0; i < WOLFHSM_CFG_SERVER_KEYCACHE_COUNT; i++) {
+                if (ctx->cache[i].meta->id != WH_KEYID_ERASED) {
+                    evictRet =
+                        _EvictSlot(ctx->cache[i].buffer, ctx->cache[i].meta);
+                    if (evictRet == WH_ERROR_OK) {
+                        foundIndex = i;
+                        break;
+                    }
+                }
+            }
+        }
+
         /* Zero slot and capture pointers */
         if (foundIndex >= 0) {
             memset(&ctx->cache[foundIndex], 0, sizeof(whCacheSlot));
@@ -347,6 +366,22 @@ static int _GetKeyCacheSlot(whKeyCacheContext* ctx, uint16_t keySz,
             }
         }
 
+        /* Last-resort fallback: reclaim any non-erased big-cache slot
+         * when no committed slot is evictable. See the matching block in
+         * the regular cache path above. */
+        if (foundIndex == -1) {
+            for (i = 0; i < WOLFHSM_CFG_SERVER_KEYCACHE_BIG_COUNT; i++) {
+                if (ctx->bigCache[i].meta->id != WH_KEYID_ERASED) {
+                    evictRet = _EvictSlot(ctx->bigCache[i].buffer,
+                                          ctx->bigCache[i].meta);
+                    if (evictRet == WH_ERROR_OK) {
+                        foundIndex = i;
+                        break;
+                    }
+                }
+            }
+        }
+
         /* Zero slot and capture pointers */
         if (foundIndex >= 0) {
             memset(&ctx->bigCache[foundIndex], 0, sizeof(whBigCacheSlot));