Re: [PATCH] signal: propagate __user annotations properly

[Lukas Bulwahn <lukas.bulwahn@gmail.com>]

On Mon, Dec 7, 2020 at 2:04 PM Christian Brauner
<christian.brauner@ubuntu.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@gmail.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