efifb: exit if framebuffer address is invalid

efifb will attempt to ioremap a framebuffer even if its starting address
is 0, failing and causing an ugly backtrace in the process.  Exit before
probing if this is the case.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Peter Jones <pjones@redhat.com>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/video/efifb.c b/drivers/video/efifb.c
index 0c5b9a9fd56f..8dea2bc92705 100644
--- a/drivers/video/efifb.c
+++ b/drivers/video/efifb.c
@@ -210,12 +210,15 @@ static int __init efifb_probe(struct platform_device *dev)
         unsigned int size_total;
         int request_succeeded = 0;
 
-        printk(KERN_INFO "efifb: probing for efifb\n");
-
         if (!screen_info.lfb_depth)
                 screen_info.lfb_depth = 32;
         if (!screen_info.pages)
                 screen_info.pages = 1;
+        if (!screen_info.lfb_base) {
+                printk(KERN_DEBUG "efifb: invalid framebuffer address\n");
+                return -ENODEV;
+        }
+        printk(KERN_INFO "efifb: probing for efifb\n");
 
         /* just assume they're all unset if any are */
         if (!screen_info.blue_size) {