From: Javier Martinez Canillas <javierm@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Maxime Ripard <maxime@cerno.tech>,
Thomas Zimmermann <tzimmermann@suse.de>,
Javier Martinez Canillas <javierm@redhat.com>,
Alex Deucher <alexander.deucher@amd.com>,
Changcheng Deng <deng.changcheng@zte.com.cn>,
Daniel Vetter <daniel@ffwll.ch>,
Guenter Roeck <linux@roeck-us.net>, Helge Deller <deller@gmx.de>,
Sam Ravnborg <sam@ravnborg.org>,
Zhen Lei <thunder.leizhen@huawei.com>,
Zheyu Ma <zheyuma97@gmail.com>,
dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org
Subject: [PATCH 2/2] fbdev: Make fb_release() return -ENODEV if fbdev was unregistered
Date: Mon, 2 May 2022 15:09:44 +0200 [thread overview]
Message-ID: <20220502130944.363776-3-javierm@redhat.com> (raw)
In-Reply-To: <20220502130944.363776-1-javierm@redhat.com>
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>
---
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)
--
2.35.1
next prev parent reply other threads:[~2022-05-02 13:10 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 ` Javier Martinez Canillas [this message]
2022-05-02 13:20 ` [PATCH 2/2] fbdev: Make fb_release() return -ENODEV if fbdev was unregistered Thomas Zimmermann
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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