From: Mark Rutland <mark.rutland@arm.com>
To: David Laight <David.Laight@ACULAB.COM>
Cc: 'Szabolcs Nagy' <szabolcs.nagy@arm.com>,
Theodore Ts'o <tytso@mit.edu>,
"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: linux interprets an fcntl int arg as long
Date: Tue, 1 Nov 2022 13:12:39 +0000 [thread overview]
Message-ID: <Y2EbR6YnQcgK4B8T@FVFF77S0Q05N> (raw)
In-Reply-To: <0030a20a94cd49628c5461d044bb28ed@AcuMS.aculab.com>
On Tue, Nov 01, 2022 at 12:19:51PM +0000, David Laight wrote:
> From: 'Szabolcs Nagy' <szabolcs.nagy@arm.com>
> > Sent: 01 November 2022 11:45
> >
> > The 11/01/2022 10:02, David Laight wrote:
> > > From: Szabolcs Nagy
> > kernel code:
> > ------------
> > SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
> > {
>
> That is just a wrapper and calls do_fcntl().
> which needs changing to be add:
> arg &= ~0U;
> before the switch(cmd) {
Just to check, do you mean the switch in do_fcntl(), or the switch within memfd_fcntl() ?
The former handles other APIs which do expect arg to be a long (e.g.
F_SET_RW_HINT and F_GET_RW_HINT expect it to hold a full 64-bit pointer), so
that'd break things.
The latter would work (as would casting arg to int when calling
memfd_add_seals()).
Mark.
next prev parent reply other threads:[~2022-11-01 13:12 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-31 12:44 linux interprets an fcntl int arg as long Szabolcs Nagy
2022-11-01 1:46 ` Theodore Ts'o
2022-11-01 9:11 ` Szabolcs Nagy
2022-11-01 10:02 ` David Laight
2022-11-01 11:44 ` 'Szabolcs Nagy'
2022-11-01 12:19 ` David Laight
2022-11-01 12:49 ` 'Szabolcs Nagy'
2022-11-01 13:12 ` Mark Rutland [this message]
2022-11-01 13:29 ` David Laight
2022-11-01 13:35 ` David Laight
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