# Re: start switching sysfs attributes to expose the seq\_file

- From: Bart Van Assche \<bvanassche@acm.org\>
- Date: 2021-09-13 16:40:01 
- List: linux-block
- Page: https://ratatoskr.run/linux-block/2021/09/214072
- Thread: https://ratatoskr.run/linux-block/2021/09/214031/t.md

```text
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@acm.org/).

Bart.
```