Re: start switching sysfs attributes to expose the seq_file

[Bart Van Assche]

On 9/13/21 09:46, Greg Kroah-Hartman wrote:
> On Mon, Sep 13, 2021 at 09:39:56AM -0700, Bart Van Assche wrote:
> > On 9/12/21 10:41 PM, Christoph Hellwig wrote:
> > > Al pointed out multiple times that seq_get_buf is highly dangerous as
> > > it opens up the tight seq_file abstractions to buffer overflows.  The
> > > last such caller now is sysfs.
> > >
> > > This series allows attributes to implement a seq_show method and switch
> > > the block and XFS code as users that I'm most familiar with to use
> > > seq_files directly after a few preparatory cleanups.  With this series
> > > "leaf" users of sysfs_ops can be converted one at at a time, after that
> > > we can move the seq_get_buf into the multiplexers (e.g. kobj, device,
> > > class attributes) and remove the show method in sysfs_ops and repeat the
> > > process until all attributes are converted.  This will probably take a
> > > fair amount of time.
> >
> > Hi Christoph,
> >
> > Thanks for having done this work. In case you would need it, some time ago
> > I posted the following sysfs patch but did not receive any feedback:
> > "[PATCH] kernfs: Improve lockdep annotation for files which implement mmap"
> > (https://lore.kernel.org/linux-kernel/20191004161124.111376-1-bvanassche@xxxxxxx/).
>
> That was from back in 2019, sorry I must have missed it.
>
> Care to rebase and resend it if it is still needed?

Hi Greg,

I think that patch is still relevant. It removes some ugly code from 
sysfs. I will rebase, retest and resend it.

Thanks,

Bart.