linux-kernel - [PATCH 1/2] Check if start address is in vma region in NOMMU function get_user

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Message-Id: <20060901124207.26038.24367.stgit@warthog.cambridge.redhat.com>
Date:	Fri, 01 Sep 2006 13:42:07 +0100
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org, akpm@...l.org
Cc:	linux-kernel@...r.kernel.org, uclinux-dev@...inux.org,
	dhowells@...hat.com
Subject: [PATCH 1/2] Check if start address is in vma region in NOMMU function get_user_pages().

From: Sonic Zhang <sonic.adi@...il.com>

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>
Signed-Off-By: David Howells <dhowells@...hat.com>
---

 mm/nommu.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/nommu.c b/mm/nommu.c
index 3215f46..2fe3fe4 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -129,16 +129,20 @@ int get_user_pages(struct task_struct *t
 	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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