linux-kernel - Re: [PATCH v12 2/3] ptrace,syscall_user_dispatch: checkpoint/restore support for SUD

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Date:   Tue, 28 Feb 2023 17:52:40 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     Dmitry Safonov <0x7f454c46@...il.com>
Cc:     Gregory Price <gourry.memverge@...il.com>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        avagin@...il.com, peterz@...radead.org, luto@...nel.org,
        krisman@...labora.com, tglx@...utronix.de, corbet@....net,
        shuah@...nel.org, Gregory Price <gregory.price@...verge.com>
Subject: Re: [PATCH v12 2/3] ptrace,syscall_user_dispatch: checkpoint/restore
 support for SUD

On 02/27, Dmitry Safonov wrote:
>
> > +int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long size,
> > +                                    void __user *data)
> > +{
> > +       int rc;
> > +       struct ptrace_sud_config cfg;
> > +
> > +       if (size != sizeof(struct ptrace_sud_config))
> > +               return -EINVAL;
> > +
> > +       if (copy_from_user(&cfg, data, sizeof(struct ptrace_sud_config)))
> > +               return -EFAULT;
>
> It seems that the tool you want here would be copy_struct_from_user(),
> which is designed for extendable syscalls.

Hmm. Why?

In this case ksize == usize, so why do we need copy_struct_from_user ?

Oleg.