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* [gcc r13-590] [Ada] Prevent overflow in computation of aggregate size
@ 2022-05-18 8:43 Pierre-Marie de Rodat
0 siblings, 0 replies; only message in thread
From: Pierre-Marie de Rodat @ 2022-05-18 8:43 UTC (permalink / raw)
To: gcc-cvs
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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