[PATCH 05/43] fbdev/deferred-io: Test smem_start for I/O memory

[Thomas Zimmermann]

Test smem_start before looking up pages from its value. Return
NULL if it is unset. This will result in a SIGBUS signal.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/video/fbdev/core/fb_defio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c
index b38f775cd39dd..fe84218ded457 100644
--- a/drivers/video/fbdev/core/fb_defio.c
+++ b/drivers/video/fbdev/core/fb_defio.c
@@ -26,11 +26,11 @@
 static struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs)
 {
 	const void *screen_buffer = info->screen_buffer;
-	struct page *page;
+	struct page *page = NULL;
 
 	if (is_vmalloc_addr(screen_buffer + offs))
 		page = vmalloc_to_page(screen_buffer + offs);
-	else
+	else if (info->fix.smem_start)
 		page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT);
 
 	return page;
-- 
2.44.0