[patch 126/146] mm/damon/schemes: add the validity judgment of thresholds

[Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>]

From: Xin Hao <xhao@xxxxxxxxxxxxxxxxx>
Subject: mm/damon/schemes: add the validity judgment of thresholds

In dbgfs "schemes" interface, i do some test like this:
    # cd /sys/kernel/debug/damon
    # echo "2 1 2 1 10 1 3 10 1 1 1 1 1 1 1 1 2 3" > schemes
    # cat schemes
    # 2 1 2 1 10 1 3 10 1 1 1 1 1 1 1 1 2 3 0 0

There have some unreasonable places, i set the valules of these variables
"<min_sz, max_sz> <min_nr_a, max_nr_a>, <min_age, max_age>, <wmarks.high,
wmarks.mid, wmarks.low>" as "<2, 1>, <2, 1>, <10, 1>, <1, 2, 3>.

So there add a validity judgment for these thresholds value.

Link: https://lkml.kernel.org/r/d78360e52158d786fcbf20bc62c96785742e76d3.1637239568.git.xhao@xxxxxxxxxxxxxxxxx
Signed-off-by: Xin Hao <xhao@xxxxxxxxxxxxxxxxx>
Reviewed-by: SeongJae Park <sj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/damon/dbgfs.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/mm/damon/dbgfs.c~mm-damon-schemes-add-the-validity-judgment-of-thresholds
+++ a/mm/damon/dbgfs.c
@@ -213,6 +213,13 @@ static struct damos **str_to_schemes(con
 		if (!damos_action_valid(action))
 			goto fail;
 
+		if (min_sz > max_sz || min_nr_a > max_nr_a || min_age > max_age)
+			goto fail;
+
+		if (wmarks.high < wmarks.mid || wmarks.high < wmarks.low ||
+		    wmarks.mid <  wmarks.low)
+			goto fail;
+
 		pos += parsed;
 		scheme = damon_new_scheme(min_sz, max_sz, min_nr_a, max_nr_a,
 				min_age, max_age, action, &quota, &wmarks);
_