@@ -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;
}
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> --- Changes in v3: - Only move framebuffer_release() and don't do any other change (Daniel Vetter). Changes in v2: - Also do the change for vesafb (Thomas Zimmermann). drivers/video/fbdev/vesafb.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)