Re: kern/49692: impossibly large mmap does not fail

[Justin Cormack <justin%specialbusservice.com@localhost>]

On 1 March 2015 at 06:40, David Holland <dholland-bugs%netbsd.org@localhost> wrote:
> The following reply was made to PR kern/49692; it has been noted by GNATS.
>
> From: David Holland <dholland-bugs%netbsd.org@localhost>
> To: gnats-bugs%NetBSD.org@localhost
> Cc:
> Subject: Re: kern/49692: impossibly large mmap does not fail
> Date: Sun, 1 Mar 2015 06:35:08 +0000
>
>  On Tue, Feb 24, 2015 at 07:05:00PM +0000, Justin Cormack wrote:
>   >  On 24 February 2015 at 18:53, Martin Husemann <martin%duskware.de@localhost> wrote:
>   >  > Note that -1 is not a multiple of the machines PAGE_SIZE, so it gets
>   >  > rounded up to the next full page.
>   >
>   >  Ah yes, -8192 say is ok and gives ENOMEM. But it is size_t so it is
>   >  unsigned, so with *size_t)-1 that is an unsigned overflow to 0 that is
>   >  taking place, which is undefined behaviour.
>
>  Eh wut? No it isn't. It's signed overflow that's undefined.

Indeed. So it seems harmless, if unexpected, so I guess we can close it.

Justin