From: Alejandro Colomar <alx.manpages@gmail.com>
To: Theo de Raadt <deraadt@openbsd.org>
Cc: otto@cvs.openbsd.org, djm@cvs.openbsd.org,
libc-alpha@sourceware.org, "Alejandro Colomar" <alx@kernel.org>,
"Theo de Raadt" <deraadt@theos.com>,
"Todd C . Miller" <Todd.Miller@sudo.ws>,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
"Cristian Rodríguez" <crrodriguez@opensuse.org>,
"Adhemerval Zanella" <adhemerval.zanella@linaro.org>,
"Yann Droneaud" <ydroneaud@opteya.com>,
"Joseph Myers" <joseph@codesourcery.com>,
"Serge Hallyn" <serge@hallyn.com>,
"Iker Pedrosa" <ipedrosa@redhat.com>
Subject: Re: [PATCH] Give a useful meaning to arc4random_uniform(0);
Date: Sat, 31 Dec 2022 16:13:52 +0100 [thread overview]
Message-ID: <fd253fc5-d978-68aa-868f-18537d212433@gmail.com> (raw)
In-Reply-To: <ced48d59-2032-0350-916e-7740d1d53f66@gmail.com>
[-- Attachment #1.1: Type: text/plain, Size: 1599 bytes --]
Hi Theo,
On 12/31/22 15:56, Alejandro Colomar wrote:
>>
>> I do not like your proposal at all. A function like arc4random_range()
>> is even more likely to be used wrong by passing backwards points
>> and you seem to have a lot of hubris to add a range check to it.
I didn't understand the entire sentence, since I'm not a native English speaker.
Sorry for that. About adding a range check, I'm not against it. But what to
do in that case? abort()? I don't see anything significantly better? In the
Linux kernel, the used something BUILD_BUG, but I don't know those macros very much.
I'm really open to discussion about what would the the best behavior when max < min.
Cheers,
Alex
>
> Oh, I just checked hubris in the dictionary and it seems you did mention ego.
> I'll try to rebate you with something useful.
>
> If you run `grep -rn 'arc4random_uniform('` in the OpenBSD tree, there will be
> many cases where you'd really benefit from this. I'll just pick a few:
>
>
> sys/net/pf_lb.c:224:
> cut = arc4random_uniform(1 + high - low) + low;
> better as:
> cut = arc4random_range(low, high);
>
>
> sys/kern/kern_fork.c:648:
> pid = 2 + arc4random_uniform(PID_MAX - 1);
> better as:
> pid = arc4random_range(2, PID_MAX);
>
>
> usr.bin/nc/netcat.c:1501:
> cp = arc4random_uniform(x + 1);
> better as:
> cp = arc4random_range(0, x);
>
>
--
<http://www.alejandro-colomar.es/>
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next prev parent reply other threads:[~2022-12-31 15:14 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-31 2:36 Alejandro Colomar
2022-12-31 2:48 ` Alejandro Colomar
2022-12-31 2:57 ` Jason A. Donenfeld
2022-12-31 13:39 ` Alejandro Colomar
2022-12-31 8:50 ` Theo de Raadt
2022-12-31 8:51 ` Theo de Raadt
2022-12-31 14:56 ` Alejandro Colomar
2022-12-31 15:13 ` Alejandro Colomar [this message]
2022-12-31 15:17 ` Alejandro Colomar
2022-12-31 15:59 ` Alejandro Colomar
2022-12-31 16:03 ` Alejandro Colomar
2023-01-01 8:41 ` Theo de Raadt
2022-12-31 23:07 ` Damien Miller
2022-12-31 23:58 ` Alejandro Colomar
2023-01-01 7:48 ` Ariadne Conill
2023-01-01 9:21 ` Otto Moerbeek
2023-01-01 14:05 ` Alejandro Colomar
2023-01-01 8:34 ` Theo de Raadt
2023-01-01 21:37 ` Arsen Arsenović
2023-01-01 23:50 ` Alejandro Colomar
2023-01-02 0:02 ` Arsen Arsenović
2023-01-02 11:24 ` Alejandro Colomar
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