From ff176fa509aeb88a7b3b2bb0f1a8170af104acbe Mon Sep 17 00:00:00 2001
From: Igor Zolotarev <i.zolotarev@corp.mail.ru>
Date: Wed, 8 Dec 2021 19:44:49 +0300
Subject: [PATCH] Add upper constraint to quicksort

---
 metrics/quantile.lua   |  2 ++
 test/quantile_test.lua | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/metrics/quantile.lua b/metrics/quantile.lua
index ee1c380c..3460cbdc 100644
--- a/metrics/quantile.lua
+++ b/metrics/quantile.lua
@@ -13,6 +13,8 @@ local sample_constructor = ffi.typeof('sample')
 
 local function quicksort(array, low, high)
     assert(low >= 0, 'Low bound must be non-negative')
+    assert(high < ffi.sizeof(array) / ffi.sizeof('double'),
+        'Upper bound must be lower than array size')
     if high - low < 1 then
         return array
     end
diff --git a/test/quantile_test.lua b/test/quantile_test.lua
index 00dcc2c2..861b1325 100644
--- a/test/quantile_test.lua
+++ b/test/quantile_test.lua
@@ -109,6 +109,17 @@ g.test_low_bound_negative = function()
     )
 end
 
+g.test_high_bound_higher_array_size = function()
+    local empty = ffi.new('double[?]', 2)
+    t.assert_error_msg_contains(
+        'Upper bound must be lower than array size',
+        quantile.quicksort,
+        empty,
+        1,
+        10
+    )
+end
+
 g.test_not_sorted = function()
     local array = ffi.new('double[?]', 2)
     array[0] = math.huge