Further fbcon sanity checking

This moves the

    if (num_registered_fb == FB_MAX)
            return -ENXIO;

check _AFTER_ the call to do_remove_conflicting_framebuffers() as this
would (now in a safe way) allow a native driver to replace the
conflicting one even if all slots in registered_fb[] are taken.

This also prevents unregistering a framebuffer that is no longer
registered (vga16f will unregister at module unload time even if the
frame buffer had been unregistered earlier due to being found
conflicting).

Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 46ee5e5a08c6..5aac00eb1830 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1573,15 +1573,15 @@ static int do_register_framebuffer(struct fb_info *fb_info)
         struct fb_event event;
         struct fb_videomode mode;
 
-        if (num_registered_fb == FB_MAX)
-                return -ENXIO;
-
         if (fb_check_foreignness(fb_info))
                 return -ENOSYS;
 
         do_remove_conflicting_framebuffers(fb_info->apertures, fb_info->fix.id,
                                          fb_is_primary_device(fb_info));
 
+        if (num_registered_fb == FB_MAX)
+                return -ENXIO;
+
         num_registered_fb++;
         for (i = 0 ; i < FB_MAX; i++)
                 if (!registered_fb[i])
@@ -1639,7 +1639,7 @@ static int do_unregister_framebuffer(struct fb_info *fb_info)
         int i, ret = 0;
 
         i = fb_info->node;
-        if (!registered_fb[i])
+        if (i < 0 || i >= FB_MAX || registered_fb[i] != fb_info)
                 return -EINVAL;
 
         if (!lock_fb_info(fb_info))