lkml.org 
[lkml]   [2006]   [Sep]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH]i386: fix overflow in vmap on an x86 system which has more than 4GB memory.
This is a 2.4 fix (not needed in 2.6): let's CC maintainer Willy Tarreau.

On Fri, 15 Sep 2006, Anatoli Antonovitch wrote:

> Description
> (max_mapnr << PAGE_SHIFT) would overflow on an x86 system which has more
> than 4GB memory, and hence cause vmap to fail every time.

Good point, thanks for the patch. Sorry I'm so slow to get to it.

>
> Signed-off-by: Michael Chen <micche@ati.com>
>
> Patch
> diff -Nur linux-2.4.21-40.EL/mm/vmalloc.c
> linux-2.4.21-40.EL.diff/mm/vmalloc.c
> --- linux-2.4.21-40.EL/mm/vmalloc.c 2006-02-02 21:13:20.000000000
> -0600
> +++ linux-2.4.21-40.EL.diff/mm/vmalloc.c 2006-09-04

And still needs fixing in latest mainline 2.4.

> 11:29:33.000000000 -0500
> @@ -298,8 +298,8 @@
> struct vm_struct *area;
> unsigned long size = count << PAGE_SHIFT;
>
> - if (!size || size > (max_mapnr << PAGE_SHIFT))
> - return NULL;
> + if (!count || count > max_mapnr)
> + return NULL;

I'm afraid the tabs got messed up in both the old and new lines.
Also, count is a signed int (whereas size and max_mapnr are both
unsigned longs), so best reject "count <= 0" rather than just "!count".

> area = get_vm_area(size, flags);
> if (!area) {
> return NULL;

Here's a replacement patch for Willy. Anatoli, you didn't sign
off the patch yourself: so I'm assuming Michael is the originator.


From: Michael Chen <micche@ati.com>

(max_mapnr << PAGE_SHIFT) would overflow on a system which has
4GB memory or more, and so could cause vmap to fail every time.

Signed-off-by: Michael Chen <micche@ati.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
---

mm/vmalloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- 2.4.34-pre3/mm/vmalloc.c 2004-04-14 14:05:41.000000000 +0100
+++ linux/mm/vmalloc.c 2006-09-23 17:52:59.000000000 +0100
@@ -293,7 +293,7 @@ void * vmap(struct page **pages, int cou
struct vm_struct *area;
unsigned long size = count << PAGE_SHIFT;

- if (!size || size > (max_mapnr << PAGE_SHIFT))
+ if (count <= 0 || count > max_mapnr)
return NULL;
area = get_vm_area(size, flags);
if (!area) {
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2006-09-23 19:29    [W:0.045 / U:1.100 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site