Date: Mon, 10 Jun 2019 09:57:56 -0500 From: Doug Moore <unkadoug@gmail.com> To: Shawn Webb <shawn.webb@hardenedbsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org, pho@freebsd.org Subject: Re: svn commit: r348843 - head/sys/vm Message-ID: <65cab520-731a-3256-8a71-bb8cfcc93011@gmail.com> In-Reply-To: <20190610142715.be254wljfrnetuom@mutt-hbsd> References: <201906100307.x5A37BFt099669@repo.freebsd.org> <20190610130034.k2nzitvaxvpj5lzx@mutt-hbsd> <c084ec12-5f44-c3e1-bad0-2c702a3032f9@freebsd.org> <20190610142715.be254wljfrnetuom@mutt-hbsd>
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The comment and the code that rejects size==0, or doesn't, are copied
below. Konstantin Belousov is the last person to have touched most of
it, and can better explain its meaning than I.
Doug Moore
/*
* Enforce the constraints.
* Mapping of length 0 is only allowed for old binaries.
* Anonymous mapping shall specify -1 as filedescriptor and
* zero position for new code. Be nice to ancient a.out
* binaries and correct pos for anonymous mapping, since old
* ld.so sometimes issues anonymous map requests with non-zero
* pos.
*/
if (!SV_CURPROC_FLAG(SV_AOUT)) {
if ((size == 0 && curproc->p_osrel >= P_OSREL_MAP_ANON) ||
((flags & MAP_ANON) != 0 && (fd != -1 || pos != 0)))
return (EINVAL);
} else {
if ((flags & MAP_ANON) != 0)
pos = 0;
}
On 6/10/19 9:27 AM, Shawn Webb wrote:
> Sounds good! I think the manpage still might still need a change
> to match the current behavior, or perhaps matching something similar
> to that vm_mmap.c comment. But that comment brings another question:
> what's the definition of "old binaries"? a.out?
>
> Thanks,
>
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