Hi Team, There are potential NULL pointer dereferences, checks should be implemented to the return value of function sqlite3ExprSkipCollateAndLikely. A similar problem has been fixed in [check-in:5aeb5a2d]. In function resolveCompoundOrderBy in /src/resolve.c, Expr *pE, *pDup; if( pItem->done ) continue; pE = sqlite3ExprSkipCollateAndLikely(pItem->pExpr); if( sqlite3ExprIsInteger(pE, &iCol) ){ if( iCol<=0 || iCol>pEList->nExpr ){ resolveOutOfRangeError(pParse, "ORDER", i+1, pEList->nExpr); return 1; } }else{ iCol = resolveAsName(pParse, pEList, pE); In function resolveCompoundOrderBy in /src/resolve.c, Expr *pE2 = sqlite3ExprSkipCollateAndLikely(pE); if( zType[0]!='G' ){ iCol = resolveAsName(pParse, pSelect->pEList, pE2); In function findIndexCol in /src/where.c, Expr *p = sqlite3ExprSkipCollateAndLikely(pList->a[i].pExpr); if( p->op==TK_COLUMN && p->iColumn==pIdx->aiColumn[iCol] && p->iTable==iBase In function isDistinctRedundant in /src/where.c, for(i=0; i<pDistinct->nExpr; i++){ Expr *p = sqlite3ExprSkipCollateAndLikely(pDistinct->a[i].pExpr); if( p->op==TK_COLUMN && p->iTable==iBase && p->iColumn<0 ) return 1; } In function indexMightHelpWithOrderBy in /src/where.c, Expr *pExpr = sqlite3ExprSkipCollateAndLikely(pOB->a[ii].pExpr); if( pExpr->op==TK_COLUMN && pExpr->iTable==iCursor ){ if( pExpr->iColumn<0 ) return 1; for(jj=0; jj<pIndex->nKeyCol; jj++){ if( pExpr->iColumn==pIndex->aiColumn[jj] ) return 1; } In function exprToRegister in /src/expr.c, Expr *p = sqlite3ExprSkipCollateAndLikely(pExpr); p->op2 = p->op; p->op = TK_REGISTER; p->iTable = iReg; ExprClearProperty(p, EP_Skip); In function sqlite3ExprCodeTemp in /src/expr.c, pExpr = sqlite3ExprSkipCollateAndLikely(pExpr); if( ConstFactorOk(pParse) && pExpr->op!=TK_REGISTER && sqlite3ExprIsConstantNotJoin(pExpr) ){