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| author | Javier Martinez Canillas <javierm@redhat.com> | 2022-05-26 21:47:52 +0200 |
|---|---|---|
| committer | Helge Deller <deller@gmx.de> | 2022-05-28 19:26:56 +0200 |
| commit | acde4003efc16480375543638484d8f13f2e99a3 (patch) | |
| tree | 53f0b69267961370c857d1d2fea9221bd765431f /drivers/video | |
| parent | 50e35bd57c02a584442c0aa917787c858eabe80b (diff) | |
| download | lwn-acde4003efc16480375543638484d8f13f2e99a3.tar.gz lwn-acde4003efc16480375543638484d8f13f2e99a3.zip | |
video: fbdev: vesafb: Fix a use-after-free due early fb_info cleanup
Commit b3c9a924aab6 ("fbdev: vesafb: Cleanup fb_info in .fb_destroy rather
than .remove") fixed a use-after-free error due the vesafb driver freeing
the fb_info in the .remove handler instead of doing it in .fb_destroy.
This can happen if the .fb_destroy callback is executed after the .remove
callback, since the former tries to access a pointer freed by the latter.
But that change didn't take into account that another possible scenario is
that .fb_destroy is called before the .remove callback. For example, if no
process has the fbdev chardev opened by the time the driver is removed.
If that's the case, fb_info will be freed when unregister_framebuffer() is
called, making the fb_info pointer accessed in vesafb_remove() after that
to no longer be valid.
To prevent that, move the expression containing the info->par to happen
before the unregister_framebuffer() function call.
Fixes: b3c9a924aab6 ("fbdev: vesafb: Cleanup fb_info in .fb_destroy rather than .remove")
Reported-by: Pascal Ernster <dri-devel@hardfalcon.net>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Pascal Ernster <dri-devel@hardfalcon.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'drivers/video')
| -rw-r--r-- | drivers/video/fbdev/vesafb.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/video/fbdev/vesafb.c b/drivers/video/fbdev/vesafb.c index e25e8de5ff67..929d4775cb4b 100644 --- a/drivers/video/fbdev/vesafb.c +++ b/drivers/video/fbdev/vesafb.c @@ -490,11 +490,12 @@ 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); + /* vesafb_destroy takes care of info cleanup */ + unregister_framebuffer(info); + return 0; } |