[PATCH] Check if start address is in vma region in NOMMU function get_user_pages().

[Sonic Zhang]

Hi,

In NOMMU arch, if run "cat /proc/self/mem", data from physical address
0 are read. This behavior is different from MMU arch.  In IA32,
message "cat: /proc/self/mem: Input/output error" is reported.

This issue is rootcaused by not validate the start address in NOMMU
function get_user_pages(). Following patch solves this issue.

Thanks

Sonic Zhang


Signed-off-by: Sonic Zhang <sonic.adi@xxxxxxxxx>

--- linux-2.6.x/mm/nommu.c	2006-08-31 15:53:09.269952304 +0800
+++ linux-2.6.x/mm/nommu.c	2006-08-31 15:49:58.634933232 +0800
@@ -138,16 +138,20 @@
	struct page **pages, struct vm_area_struct **vmas)
{
	int i;
-	static struct vm_area_struct dummy_vma;
+	struct vm_area_struct *vma;

	for (i = 0; i < len; i++) {
+		vma = find_vma(mm, start);
+		if(!vma)
+			return i ? : -EFAULT;
+		
		if (pages) {
			pages[i] = virt_to_page(start);
			if (pages[i])
				page_cache_get(pages[i]);
		}
		if (vmas)
-			vmas[i] = &dummy_vma;
+			vmas[i] = vma;
		start += PAGE_SIZE;
	}
	return(i);
-
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