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| author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2022-05-06 00:04:13 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-05-25 09:57:35 +0200 |
| commit | 4f631f9f9d08a7c6e47d2f19d866435fe70c3db5 (patch) | |
| tree | 793c6e6cadb3cbec9981bf2a43387a77f196109a | |
| parent | 92dc6278dec983f7dfc33f28bb929d5ca92087ac (diff) | |
| download | linux-4f631f9f9d08a7c6e47d2f19d866435fe70c3db5.tar.gz linux-4f631f9f9d08a7c6e47d2f19d866435fe70c3db5.tar.bz2 linux-4f631f9f9d08a7c6e47d2f19d866435fe70c3db5.zip | |
fbdev: Prevent possible use-after-free in fb_release()
[ Upstream commit 89bfd4017e58faaf70411555e7f508495114e90b ]
Most fbdev drivers have issues with the fb_info lifetime, because call to
framebuffer_release() from their driver's .remove callback, rather than
doing from fbops.fb_destroy callback.
Doing that will destroy the fb_info too early, while references to it may
still exist, leading to a use-after-free error.
To prevent this, check the fb_info reference counter when attempting to
kfree the data structure in framebuffer_release(). That will leak it but
at least will prevent the mentioned error.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220505220413.365977-1-javierm@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/video/fbdev/core/fbsysfs.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c index 65dae05fff8e..ce699396d6ba 100644 --- a/drivers/video/fbdev/core/fbsysfs.c +++ b/drivers/video/fbdev/core/fbsysfs.c @@ -80,6 +80,10 @@ void framebuffer_release(struct fb_info *info) { if (!info) return; + + if (WARN_ON(refcount_read(&info->count))) + return; + kfree(info->apertures); kfree(info); } |