agp: zero pages before sending to userspace

AGP pages might be mapped into userspace finally, so the pages should be
set to zero before userspace can use it. Otherwise there is potential
information leakage.

Signed-off-by: Shaohua Li <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

drivers/char/agp/generic.c

···
 	int i, ret = -ENOMEM;
 
 	for (i = 0; i < num_pages; i++) {
-		page = alloc_page(GFP_KERNEL | GFP_DMA32);
+		page = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);
 		/* agp_free_memory() needs gart address */
 		if (page == NULL)
 			goto out;
···
 {
 	struct page * page;
 
-	page = alloc_page(GFP_KERNEL | GFP_DMA32);
+	page = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);
 	if (page == NULL)
 		return NULL;