[dm-devel] [PATCH] compat_ioctl: fix reimplemented SG_IO handling causing -EINVAL from sg_io()

[Arnd Bergmann]

On Wed, Sep 18, 2019 at 5:35 PM Steffen Maier <maier at linux.ibm.com> wrote:
>
> scsi_cmd_ioctl() had hdr as on stack auto variable and called
> copy_{from,to}_user with the address operator &hdr and sizeof(hdr).
>
> After the refactoring, {get,put}_sg_io_hdr() takes a pointer &hdr.
> So the copy_{from,to}_user within the new helper functions should
> just take the given pointer argument hdr and sizeof(*hdr).
>
> I saw -EINVAL from sg_io() done by /usr/lib/udev/scsi_id which could
> in turn no longer whitelist SCSI disks for devicemapper multipath.
>
> Signed-off-by: Steffen Maier <maier at linux.ibm.com>
> Fixes: 4f45155c29fd ("compat_ioctl: reimplement SG_IO handling")
> ---
>
> Arnd, I'm not sure about the sizeof(hdr32) change in the compat part in
> put_sg_io_hdr().
>
> This is for next, probably via Arnd's y2038/y2038,
> and it fixes next-20190917 for me regarding SCSI generic.

Hi Steffen,

Sorry for the long delay. I ended up not sending my pull request for
v5.4, so the bug is not there. I have now rebased my branch
on top of v5.4-rc2 and plan to send it for the v5.5 merge window.

I have folded your bugfix into my original patch, hope that's ok with
you. Tomorrow's linux-next should be fixed.

    Arnd