Merge pull request #293 from padelsbach/padelsbach/finding-146

Address chunk size issue in wh_Client_SheSecureBoot

Author: bigbrett

src/wh_client_she.c

@@ -156,6 +156,9 @@ int wh_Client_SheSecureBoot(whClientContext* c, uint8_t* bootloader,
     while (ret == 0 && bootloaderSent < bootloaderLen) {
         uint8_t* in;
         uint32_t justSent;
+        uint32_t              remaining;
+        static const uint32_t maxChunk =
+            WOLFHSM_CFG_COMM_DATA_LEN - sizeof(*updateReq);
 
         if (initResp->rc != WH_SHE_ERC_NO_ERROR) {
             return initResp->rc;
@@ -168,8 +171,8 @@ int wh_Client_SheSecureBoot(whClientContext* c, uint8_t* bootloader,
         in = (uint8_t*)(updateReq + 1);
 
         /* send what's left in the size available */
-        updateReq->sz = ((bootloaderLen - bootloaderSent) %
-                         (WOLFHSM_CFG_COMM_DATA_LEN - sizeof(*updateReq)));
+        remaining     = bootloaderLen - bootloaderSent;
+        updateReq->sz = (remaining > maxChunk) ? maxChunk : remaining;
 
         justSent = updateReq->sz;
         memcpy(in, bootloader + bootloaderSent, updateReq->sz);