When doing the sqlite3BtreeInsert() overwrite optimization, make sure the

memcpy() does not extend off the end of the page.

FossilOrigin-Name: 684ef4582ed19b2af22dda6fc085c70464f92f1b

src/btree.c

@@ -8068,6 +8068,7 @@ int sqlite3BtreeInsert(
       ** doing that is no faster then skipping this optimization and just
       ** calling dropCell() and insertCell(). */
       assert( rc==SQLITE_OK ); /* clearCell never fails when nLocal==nPayload */
+      if( oldCell+szNew > pPage->aDataEnd ) return SQLITE_CORRUPT_BKPT;
       memcpy(oldCell, newCell, szNew);
       return SQLITE_OK;
     }