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From: Greg Kroah-Hartman on 19 Mar 2010 11:30
From: David Rientjes <rientjes(a)google.com>

node_read_distance() has a BUILD_BUG_ON() to prevent buffer overruns when
the number of nodes printed will exceed the buffer length.

Each node only needs four chars: three for distance (maximum distance is
255) and one for a seperating space or a trailing newline.

Signed-off-by: David Rientjes <rientjes(a)google.com>
Cc: Ingo Molnar <mingo(a)elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>
---
drivers/base/node.c | 7 +++++--
1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index ad43185..93b3ac6 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -165,8 +165,11 @@ static ssize_t node_read_distance(struct sys_device * dev,
int len = 0;
int i;

- /* buf currently PAGE_SIZE, need ~4 chars per node */
- BUILD_BUG_ON(MAX_NUMNODES*4 > PAGE_SIZE/2);
+ /*
+ * buf is currently PAGE_SIZE in length and each node needs 4 chars
+ * at the most (distance + space or newline).
+ */
+ BUILD_BUG_ON(MAX_NUMNODES * 4 > PAGE_SIZE);

for_each_online_node(i)
len += sprintf(buf + len, "%s%d", i ? " " : "", node_distance(nid, i));
--
1.7.0.2

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