From: Thomas Zimmermann <tzimmermann@suse.de>
To: Javier Martinez Canillas <javierm@redhat.com>,
linux-kernel@vger.kernel.org
Cc: linux-fbdev@vger.kernel.org, Helge Deller <deller@gmx.de>,
Zheyu Ma <zheyuma97@gmail.com>,
Changcheng Deng <deng.changcheng@zte.com.cn>,
dri-devel@lists.freedesktop.org,
Maxime Ripard <maxime@cerno.tech>,
Zhen Lei <thunder.leizhen@huawei.com>,
Alex Deucher <alexander.deucher@amd.com>,
Sam Ravnborg <sam@ravnborg.org>,
Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH 2/2] fbdev: Make fb_release() return -ENODEV if fbdev was unregistered
Date: Mon, 2 May 2022 15:20:23 +0200 [thread overview]
Message-ID: <193c9eef-af13-219c-e5e0-2cc9469bf562@suse.de> (raw)
In-Reply-To: <20220502130944.363776-3-javierm@redhat.com>
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Am 02.05.22 um 15:09 schrieb Javier Martinez Canillas:
> A reference to the framebuffer device struct fb_info is stored in the file
> private data, but this reference could no longer be valid and must not be
> accessed directly. Instead, the file_fb_info() accessor function must be
> used since it does sanity checking to make sure that the fb_info is valid.
>
> This can happen for example if the fbdev driver was one that is using a
> framebuffer provided by the system firmware. In that case, the fbdev core
> could unregister the framebuffer device if a real video driver is probed.
>
> Reported-by: Maxime Ripard <maxime@cerno.tech>
> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
This seems like the correct thing to do in any case. Thanks for the
patch. Before merging, you should also add
Fixes: 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced
removal")
Reported-by: Junxiao Chang <junxiao.chang@intel.com>
Best regards
Thomas
> ---
>
> drivers/video/fbdev/core/fbmem.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
> index 20d8929df79f..d68097105f93 100644
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -1439,7 +1439,10 @@ fb_release(struct inode *inode, struct file *file)
> __acquires(&info->lock)
> __releases(&info->lock)
> {
> - struct fb_info * const info = file->private_data;
> + struct fb_info * const info = file_fb_info(file);
> +
> + if (!info)
> + return -ENODEV;
>
> lock_fb_info(info);
> if (info->fbops->fb_release)
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
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next prev parent reply other threads:[~2022-05-02 13:22 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-02 13:09 [PATCH 0/2] fbdev: Fix a NULL pointer dereference in fb_release() Javier Martinez Canillas
2022-05-02 13:09 ` [PATCH 1/2] fbdev: Check in file_fb_info() if the fb_info was already been freed Javier Martinez Canillas
2022-05-02 13:26 ` Thomas Zimmermann
2022-05-02 13:36 ` Javier Martinez Canillas
2022-05-02 13:09 ` [PATCH 2/2] fbdev: Make fb_release() return -ENODEV if fbdev was unregistered Javier Martinez Canillas
2022-05-02 13:20 ` Thomas Zimmermann [this message]
2022-05-02 13:39 ` Javier Martinez Canillas
2022-05-04 9:47 ` Daniel Vetter
2022-05-04 10:09 ` Javier Martinez Canillas
2022-05-04 10:15 ` Daniel Vetter
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