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Issue of the Implementation # L0022

Brief

kernel/range.c: clean_sort_range() returns incorrect result for full array

Detailed Description

clean_sort_range() should return a number of nonempty elements of range array, but if the array is full clean_sort_range() returns 0. The problem is that the number of nonempty elements is evaluated by finding the first empty element of the array. If there is no such element it returns an initial value of local variable nr_range that is zero. The bug can lead to loss of information regarding all ranges, since typically returned value of clean_sort_range() is considered as an actual number of ranges in the array after a series of add/subtract operations.

Possible solutions

 kernel/range.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN kernel/range.c~kernel-range-fix-clean_sort_range-for-the-case-of-full-array kernel/range.c
--- a/kernel/range.c~kernel-range-fix-clean_sort_range-for-the-case-of-full-array
+++ a/kernel/range.c
@@ -119,7 +119,7 @@ static int cmp_range(const void *x1, con
 
 int clean_sort_range(struct range *range, int az)
 {
-       int i, j, k = az - 1, nr_range = 0;
+       int i, j, k = az - 1, nr_range = az;
 
        for (i = 0; i < k; i++) {
                if (range[i].end)
_

Component

linux-kernel 2.6.32

Accepted

https://lkml.org/lkml/2010/11/5/264
commit

Status

Fixed in kernel 2.6.37

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