[PATCH] fbdev: efifb: Fix a use-after-free due early fb_info cleanup

[Javier Martinez Canillas]

Commit d258d00fb9c7 ("fbdev: efifb: Cleanup fb_info in .fb_destroy rather
than .remove") attempted to fix a use-after-free error due driver freeing
the fb_info in the .remove handler instead of doing it in .fb_destroy.

But ironically that change introduced yet another use-after-free since the
fb_info was still used after the free.

This should fix for good by freeing the fb_info at the end of the handler.

Fixes: d258d00fb9c7 ("fbdev: efifb: Cleanup fb_info in .fb_destroy rather than 
.remove")
Reported-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
Reported-by: Andrzej Hajda <andrzej.ha...@intel.com>
Signed-off-by: Javier Martinez Canillas <javi...@redhat.com>
---

 drivers/video/fbdev/efifb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
index cfa3dc0b4eee..b3d5f884c544 100644
--- a/drivers/video/fbdev/efifb.c
+++ b/drivers/video/fbdev/efifb.c
@@ -259,12 +259,12 @@ static void efifb_destroy(struct fb_info *info)
                        memunmap(info->screen_base);
        }
 
-       framebuffer_release(info);
-
        if (request_mem_succeeded)
                release_mem_region(info->apertures->ranges[0].base,
                                   info->apertures->ranges[0].size);
        fb_dealloc_cmap(&info->cmap);
+
+       framebuffer_release(info);
 }
 
 static const struct fb_ops efifb_ops = {
-- 
2.35.1