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Message-ID: <20190812165733.GD31560@redhat.com>
Date: Mon, 12 Aug 2019 18:57:34 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Christian Brauner <christian.brauner@...ntu.com>
Cc: Adrian Reber <areber@...hat.com>,
Eric Biederman <ebiederm@...ssion.com>,
Pavel Emelianov <xemul@...tuozzo.com>,
Jann Horn <jannh@...gle.com>,
Dmitry Safonov <0x7f454c46@...il.com>,
linux-kernel@...r.kernel.org, Andrei Vagin <avagin@...il.com>,
Mike Rapoport <rppt@...ux.ibm.com>,
Radostin Stoyanov <rstoyanov1@...il.com>
Subject: Re: [PATCH v5 1/2] fork: extend clone3() to support CLONE_SET_TID
On 08/12, Christian Brauner wrote:
> On Mon, Aug 12, 2019 at 06:37:10PM +0200, Oleg Nesterov wrote:
> > On 08/11, Adrian Reber wrote:
> > >
> > > include/linux/pid.h | 2 +-
> > > include/linux/sched/task.h | 1 +
> > > include/uapi/linux/sched.h | 1 +
> > > kernel/fork.c | 22 ++++++++++++++++++++--
> > > kernel/pid.c | 36 +++++++++++++++++++++++++++++-------
> > > 5 files changed, 52 insertions(+), 10 deletions(-)
> >
> > Looks good to me...
> >
> > A couple of nits below, but I won't insist, feel free to ignore.
> >
> > > +/*
> > > + * Different sizes of struct clone_args
> > > + */
> > > +#define CLONE3_ARGS_SIZE_V0 64
> >
> > I don't really understand why do we want the "size < CLONE3_ARGS_SIZE_V0"
> > check in copy_clone_args_from_user(), but I won't argue.
>
> To make sure a user can't give us a garbage sized struct that is smaller
> than the initial version of the struct.
But why do we want to detect this case?
And why CLONE3_ARGS_SIZE_V0 is special?
Oleg.
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