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| author | Javier Martinez Canillas <javierm@redhat.com> | 2022-05-06 01:05:40 +0300 |
|---|---|---|
| committer | Javier Martinez Canillas <javierm@redhat.com> | 2022-05-06 10:21:22 +0300 |
| commit | d258d00fb9c7c0cdf9d10c1ded84f10339d2d349 (patch) | |
| tree | 8bc8c745a09b79b90b27fb8b7313c9cd4e57cdad | |
| parent | 666b90b3ce9e4aac1e1deba266c3a230fb3913b0 (diff) | |
| download | linux-d258d00fb9c7c0cdf9d10c1ded84f10339d2d349.tar.xz | |
fbdev: efifb: 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/20220505220540.366218-1-javierm@redhat.com
| -rw-r--r-- | drivers/video/fbdev/efifb.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c index ea42ba6445b2..cfa3dc0b4eee 100644 --- a/drivers/video/fbdev/efifb.c +++ b/drivers/video/fbdev/efifb.c @@ -243,6 +243,10 @@ error: static inline void efifb_show_boot_graphics(struct fb_info *info) {} #endif +/* + * 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 efifb_destroy(struct fb_info *info) { if (efifb_pci_dev) @@ -254,6 +258,9 @@ static void efifb_destroy(struct fb_info *info) else memunmap(info->screen_base); } + + framebuffer_release(info); + if (request_mem_succeeded) release_mem_region(info->apertures->ranges[0].base, info->apertures->ranges[0].size); @@ -620,9 +627,9 @@ static int efifb_remove(struct platform_device *pdev) { struct fb_info *info = platform_get_drvdata(pdev); + /* efifb_destroy takes care of info cleanup */ unregister_framebuffer(info); sysfs_remove_groups(&pdev->dev.kobj, efifb_groups); - framebuffer_release(info); return 0; } |