From: Szabolcs Nagy <nsz@port70.net>
To: musl@lists.openwall.com
Subject: Re: [PATCH] mlock2 and memfd_create
Date: Fri, 22 Jun 2018 11:10:52 +0200 [thread overview]
Message-ID: <20180622091052.GV4418@port70.net> (raw)
In-Reply-To: <20180622001602.GA13372@gmail.com>
* Andrei Vagin <avagin@gmail.com> [2018-06-21 17:16:03 -0700]:
> On Tue, Jun 19, 2018 at 10:43:14PM +0200, Szabolcs Nagy wrote:
> > +
> > +int mlock2(const void *addr, size_t len, unsigned flags)
> > +{
> > + if (flags == 0)
> > + return mlock(addr, len);
> > + return syscall(SYS_mlock2, addr, len, flags);
>
> I would prefer another way to support old kernels:
>
> int ret;
>
> ret = syscall(SYS_mlock2, addr, len, flags);
> if (ret == -1 && errno == ENOSYS && flags == 0)
> return mlock(addr, len);
> return ret;
>
> This way works a bit slower on old kernels, but it doesn't have side
> effects if mlock2 is supported.
>
> For example, the user can set seccomp rules, and he will not expect that
> the mlock syscall will be executed, when he calls mlock2() in a code.
>
mlock2 is documented to be equivalent to mlock if flags==0,
the glibc logic is the same and seccomp (or whatever else
operating on the syscall layer) has to deal with mlock
anyway (unless we change the mlock implementation too).
so i would not be too worried about this.
next prev parent reply other threads:[~2018-06-22 9:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-19 20:43 Szabolcs Nagy
2018-06-22 0:16 ` Andrei Vagin
2018-06-22 9:10 ` Szabolcs Nagy [this message]
2018-06-22 17:58 ` Andrei Vagin
2018-06-22 18:25 ` Szabolcs Nagy
2018-06-22 19:02 ` Rich Felker
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