diff options
| author | Javier Martinez Canillas | 2022-05-06 00:06:31 +0200 |
|---|---|---|
| committer | Javier Martinez Canillas | 2022-05-06 09:25:49 +0200 |
| commit | b3c9a924aab61adbc29df110006aa03afe1a78ba (patch) | |
| tree | 76009b13f886aeb9c9e857251b9d28da3028fe57 /drivers/video | |
| parent | d258d00fb9c7c0cdf9d10c1ded84f10339d2d349 (diff) | |
fbdev: vesafb: Cleanup fb_info in .fb_destroy rather than .remove
The driver is calling framebuffer_release() in its .remove callback, but
this will cause the struct fb_info to be freed too early. Since it could
be that a reference is still hold to it if user-space opened the fbdev.
This would lead to a use-after-free error if the framebuffer device was
unregistered but later a user-space process tries to close the fbdev fd.
To prevent this, move the framebuffer_release() call to fb_ops.fb_destroy
instead of doing it in the driver's .remove callback.
Strictly speaking, the code flow in the driver is still wrong because all
the hardware cleanupd (i.e: iounmap) should be done in .remove while the
software cleanup (i.e: releasing the framebuffer) should be done in the
.fb_destroy handler. But this at least makes to match the behavior before
commit 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal").
Fixes: 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal")
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220505220631.366371-1-javierm@redhat.com
Diffstat (limited to 'drivers/video')
| -rw-r--r-- | drivers/video/fbdev/vesafb.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/video/fbdev/vesafb.c b/drivers/video/fbdev/vesafb.c index df6de5a9dd4c..e25e8de5ff67 100644 --- a/drivers/video/fbdev/vesafb.c +++ b/drivers/video/fbdev/vesafb.c @@ -179,6 +179,10 @@ static int vesafb_setcolreg(unsigned regno, unsigned red, unsigned green, return err; } +/* + * fb_ops.fb_destroy is called by the last put_fb_info() call at the end + * of unregister_framebuffer() or fb_release(). Do any cleanup here. + */ static void vesafb_destroy(struct fb_info *info) { struct vesafb_par *par = info->par; @@ -188,6 +192,8 @@ static void vesafb_destroy(struct fb_info *info) if (info->screen_base) iounmap(info->screen_base); release_mem_region(info->apertures->ranges[0].base, info->apertures->ranges[0].size); + + framebuffer_release(info); } static struct fb_ops vesafb_ops = { @@ -484,10 +490,10 @@ static int vesafb_remove(struct platform_device *pdev) { struct fb_info *info = platform_get_drvdata(pdev); + /* vesafb_destroy takes care of info cleanup */ unregister_framebuffer(info); if (((struct vesafb_par *)(info->par))->region) release_region(0x3c0, 32); - framebuffer_release(info); return 0; } |