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Date: Tue, 11 May 2021 09:33:06 +0200
From: Szabolcs Nagy <nsz@...t70.net>
To: David CARLIER <devnexen@...il.com>, g@...t70.net
Cc: musl@...ts.openwall.com
Subject: Re: [PATCH 1/1] reallocarray casting overflow check
explicitally
* David CARLIER <devnexen@...il.com> [2021-05-10 20:48:26 +0100]:
> From 04e3caa580cfe501ad00d85d63040de329962823 Mon Sep 17 00:00:00 2001
> From: David Carlier <devnexen@...il.com>
> Date: Mon, 10 May 2021 20:45:12 +0100
> Subject: [PATCH] reallocarray overflow check cast to size_t
>
> ---
> src/malloc/reallocarray.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/malloc/reallocarray.c b/src/malloc/reallocarray.c
> index 4a6ebe46..2556c917 100644
> --- a/src/malloc/reallocarray.c
> +++ b/src/malloc/reallocarray.c
> @@ -4,7 +4,7 @@
>
> void *reallocarray(void *ptr, size_t m, size_t n)
> {
> - if (n && m > -1 / n) {
> + if (n && m > (size_t)-1 / n) {
you need to explain this change more i think.
the usual arithmetic conversion rules of c already convert both
operands of / to size_t, unless size_t has lower conversion rank
than signed int, but such a system would have problems because
size_t was always promoted to int so you would need a lot more
casts in musl (and other software) to avoid signed int overflow
and negative arithmetics.
> errno = ENOMEM;
> return 0;
> }
> --
> 2.20.1
>
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