[Patch] statistics: fix buffer overflow in histogram with linear scale

[Martin Peschke <mp3@de.ibm.com>]

Values outside the range covered by a histogram with linear
scale resulted in invalid indices pointing to non-existing
'buckets'. Index is adjusted to array boundaries, if required.

Signed-off-by: Martin Peschke <mp3@de.ibm.com>
---

 statistic.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff -urp a/lib/statistic.c b/lib/statistic.c
--- a/lib/statistic.c	2006-10-08 23:03:56.000000000 +0200
+++ b/lib/statistic.c	2006-10-12 19:38:08.000000000 +0200
@@ -994,9 +994,12 @@ static s64 statistic_histogram_calc_valu
 
 static int statistic_histogram_calc_index_lin(struct statistic *stat, s64 value)
 {
-	unsigned long long i = value - stat->u.histogram.range_min;
+	unsigned long long i;
+	if (value <= stat->u.histogram.range_min)
+		return 0;
+	i = value - stat->u.histogram.range_min;
 	do_div(i, stat->u.histogram.base_interval);
-	return i;
+	return min(i, (unsigned long long)(stat->u.histogram.last_index));
 }
 
 static int statistic_histogram_calc_index_log2(struct statistic *stat,


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