AW: [PATCH] drm/fdinfo: Protect against driver unbind

[Tvrtko Ursulin]

On 22/04/2025 10:20, Koenig, Christian wrote:
> [AMD Official Use Only - AMD Internal Distribution Only]
> 
> Reviewed-by: Christian König <christian.koenig at amd.com>

Thanks!

I could also add:

Fixes: 3f09a0cd4ea3 ("drm: Add common fdinfo helper")
Cc: <stable at vger.kernel.org> # v6.5+

With a disclaimer that the problem predates the common helper. Not sure 
if it is worth it for such an edge case.

I was planning to merge to drm-misc-next, but if I add the stable tag it 
would be drm-misc-fixes right?

Regards,

Tvrtko

> ________________________________________
> Von: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
> Gesendet: Freitag, 18. April 2025 18:25
> An: dri-devel at lists.freedesktop.org
> Cc: kernel-dev at igalia.com; Tvrtko Ursulin; Koenig, Christian; Lucas De Marchi; Rodrigo Vivi; Umesh Nerlige Ramappa
> Betreff: [PATCH] drm/fdinfo: Protect against driver unbind
> 
> If we unbind a driver from the PCI device with an active DRM client,
> subsequent read of the fdinfo data associated with the file descriptor in
> question will not end well.
> 
> Protect the path with a drm_dev_enter/exit() pair.
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
> Cc: Christian König <christian.koenig at amd.com>
> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
> ---
>   drivers/gpu/drm/drm_file.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index c299cd94d3f7..cf2463090d3a 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -964,6 +964,10 @@ void drm_show_fdinfo(struct seq_file *m, struct file *f)
>          struct drm_file *file = f->private_data;
>          struct drm_device *dev = file->minor->dev;
>          struct drm_printer p = drm_seq_file_printer(m);
> +       int idx;
> +
> +       if (!drm_dev_enter(dev, &idx))
> +               return;
> 
>          drm_printf(&p, "drm-driver:\t%s\n", dev->driver->name);
>          drm_printf(&p, "drm-client-id:\t%llu\n", file->client_id);
> @@ -983,6 +987,8 @@ void drm_show_fdinfo(struct seq_file *m, struct file *f)
> 
>          if (dev->driver->show_fdinfo)
>                  dev->driver->show_fdinfo(&p, file);
> +
> +       drm_dev_exit(idx);
>   }
>   EXPORT_SYMBOL(drm_show_fdinfo);
> 
> --
> 2.48.0
>