linux-kernel - Re: [PATCH] signal: propagate _

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Message-ID: <CAKXUXMyC163hWT-bf=Nbw3KQspYWo_oTCNBYH-Di5ky+NU190A@mail.gmail.com>
Date:   Mon, 7 Dec 2020 14:06:17 +0100
From:   Lukas Bulwahn <lukas.bulwahn@...il.com>
To:     Christian Brauner <christian.brauner@...ntu.com>
Cc:     Christian Brauner <christian@...uner.io>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Tycho Andersen <tycho@...ho.ws>,
        Kees Cook <keescook@...omium.org>,
        David Howells <dhowells@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Serge Hallyn <serge@...lyn.com>,
        Aleksa Sarai <cyphar@...har.com>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] signal: propagate __user annotations properly

On Mon, Dec 7, 2020 at 2:04 PM Christian Brauner
<christian.brauner@...ntu.com> wrote:
>
> On Mon, Dec 07, 2020 at 01:36:10PM +0100, Lukas Bulwahn wrote:
> > Commit 3eb39f47934f ("signal: add pidfd_send_signal() syscall") introduced
> > copy_siginfo_from_user_any(), but missed to add the __user annotation to
> > the user pointer that is passed as second argument.
> >
> > Hence, when copy_siginfo_from_user_any() calls copy_siginfo_from_user(),
> > sparse warns:
> >
> >   kernel/signal.c:3716:46: warning: incorrect type in argument 2 (different address spaces)
> >   kernel/signal.c:3716:46:    expected struct siginfo const [noderef] [usertype] __user *from
> >   kernel/signal.c:3716:46:    got struct siginfo [usertype] *info
> >
> > And when pidfd_send_signal() calls copy_siginfo_from_user_any(), sparse
> > warns as well:
> >
> >   kernel/signal.c:3776:58: warning: incorrect type in argument 2 (different address spaces)
> >   kernel/signal.c:3776:58:    expected struct siginfo [usertype] *info
> >   kernel/signal.c:3776:58:    got struct siginfo [noderef] [usertype] __user *info
> >
> > Add the __user annotation to repair this chain of propagating __user
> > annotations.
> >
> > Signed-off-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
> > ---
> > applies cleanly on current master (v5.10-rc7) and next-20201204
> >
> > Christian, please pick this minor non-urgent clean-up patch.
>
> Thanks for the patch. Unfortunately I already picked up Jann's patch who
> sent it yesterday or this morning:
> https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/commit/?h=pidfd
>

Thanks for letting me know and good to know that Jann is tracking
those sparse warnings as well :)

Lukas