linux-kernel - [PATCH] Check if start address is in vma region in NOMMU function get_user

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Message-ID: <4e5ebad50608310109l489f39c0te466cfc3dbe3dc13@mail.gmail.com>
Date:	Thu, 31 Aug 2006 16:09:30 +0800
From:	"Sonic Zhang" <sonic.adi@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: [PATCH] Check if start address is in vma region in NOMMU function get_user_pages().

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@...il.com>

--- 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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