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From: Pierre-Marie de Rodat <pmderodat@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-590] [Ada] Prevent overflow in computation of aggregate size Date: Wed, 18 May 2022 08:43:22 +0000 (GMT) [thread overview] Message-ID: <20220518084322.283903857413@sourceware.org> (raw) https://gcc.gnu.org/g:16b8ba101f770503f363c095d7be5c055705b84b commit r13-590-g16b8ba101f770503f363c095d7be5c055705b84b Author: Piotr Trojanek <trojanek@adacore.com> Date: Thu Mar 31 20:56:58 2022 +0200 [Ada] Prevent overflow in computation of aggregate size When computing size of a static aggregate to decide if it should be transformed into assignments and loops we could have an overflow check. This is mostly harmless, because colossal aggregates will likely crash the application anyway, no matter how we transform them. This was not detected because compiler was built with -gnatg switch that suppresses overflow checks (they are only enabled by an explicit -gnato switch). gcc/ada/ * exp_aggr.adb (Component_Count): Calculate size as an Uint and only then check if it is in the range of Int, as otherwise the multiplication of Int values can overflow. Diff: --- gcc/ada/exp_aggr.adb | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/gcc/ada/exp_aggr.adb b/gcc/ada/exp_aggr.adb index 72f65555681..4714cab8bfa 100644 --- a/gcc/ada/exp_aggr.adb +++ b/gcc/ada/exp_aggr.adb @@ -661,10 +661,10 @@ package body Exp_Aggr is declare UI : constant Uint := - Expr_Value (Hi) - Expr_Value (Lo) + 1; + (Expr_Value (Hi) - Expr_Value (Lo) + 1) * Siz; begin if UI_Is_In_Int_Range (UI) then - return Siz * UI_To_Int (UI); + return UI_To_Int (UI); else return Int'Last; end if;
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