From ceff7a79bc7a32a3a6590f2032b3192402a6d845 Mon Sep 17 00:00:00 2001
From: John Halley Gotway <johnhg@ucar.edu>
Date: Mon, 14 Aug 2023 14:54:21 -0600
Subject: [PATCH 1/4] Per #2644, prevent reading past the end of the array.

---
 src/basic/vx_math/ptile.cc | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/basic/vx_math/ptile.cc b/src/basic/vx_math/ptile.cc
index 6bf84ce5e0..b9b0d20da9 100644
--- a/src/basic/vx_math/ptile.cc
+++ b/src/basic/vx_math/ptile.cc
@@ -64,9 +64,18 @@ double delta;
 double p = bad_data_double;
 
 if ( n > 0 ) {
+
    index = nint(floor((n - 1)*t));
-   delta = (n-1)*t - index;
-   p = (1 - delta)*ordered_array[index] + delta*ordered_array[index+1];
+
+   // Use the last value
+   if ( index == (n - 1) ) {
+      p = ordered_array[index];
+   }
+   // Interpolate linearly between two values
+   else {
+      delta = (n - 1)*t - index;
+      p = (1 - delta)*ordered_array[index] + delta*ordered_array[index + 1];
+   }
 }
 
 return ( p );
@@ -105,9 +114,15 @@ if ( n > 0 ) {
 
    index = nint(floor((n - 1)*t));
 
-   delta = (n - 1)*t - index;
-
-   p = (1 - delta)*(ordered_array[index]) + delta*(ordered_array[index + 1]);
+   // Use the last value
+   if ( index == (n - 1) ) {
+      p = ordered_array[index];
+   }
+   // Interpolate linearly between two values
+   else {
+      delta = (n - 1)*t - index;
+      p = (1 - delta)*ordered_array[index] + delta*ordered_array[index + 1];
+   }
 
 }
 

From 886d59eecc33e4a96b247b3f729e607df351b416 Mon Sep 17 00:00:00 2001
From: John Halley Gotway <johnhg@ucar.edu>
Date: Mon, 14 Aug 2023 15:32:08 -0600
Subject: [PATCH 2/4] Per #2644, additional range checking to handle bad input
 values of t.

---
 src/basic/vx_math/ptile.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/basic/vx_math/ptile.cc b/src/basic/vx_math/ptile.cc
index b9b0d20da9..75b834f934 100644
--- a/src/basic/vx_math/ptile.cc
+++ b/src/basic/vx_math/ptile.cc
@@ -72,7 +72,7 @@ if ( n > 0 ) {
       p = ordered_array[index];
    }
    // Interpolate linearly between two values
-   else {
+   else if ( index >= 0 && index < (n - 1) ) {
       delta = (n - 1)*t - index;
       p = (1 - delta)*ordered_array[index] + delta*ordered_array[index + 1];
    }
@@ -119,7 +119,7 @@ if ( n > 0 ) {
       p = ordered_array[index];
    }
    // Interpolate linearly between two values
-   else {
+   else if ( index >= 0 && index < (n - 1) ) {
       delta = (n - 1)*t - index;
       p = (1 - delta)*ordered_array[index] + delta*ordered_array[index + 1];
    }

From fa96e6f11f6d09a5eddae11366d36d543bef42f3 Mon Sep 17 00:00:00 2001
From: John Halley Gotway <johnhg@ucar.edu>
Date: Wed, 16 Aug 2023 10:57:03 -0600
Subject: [PATCH 3/4] Per #2644, error out if the requested percentile is out
 of range.

---
 src/basic/vx_math/ptile.cc | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/basic/vx_math/ptile.cc b/src/basic/vx_math/ptile.cc
index 75b834f934..9ff068b8b1 100644
--- a/src/basic/vx_math/ptile.cc
+++ b/src/basic/vx_math/ptile.cc
@@ -63,6 +63,17 @@ int index;
 double delta; 
 double p = bad_data_double;
 
+// Range check
+if ( t < 0.0 || t > 1.0 ) {
+
+   mlog << Error << "\npercentile() -> "
+        << "requested percentile value (" << t
+        << ") must be between 0 and 1!\n\n";
+
+   exit ( 1 );
+
+}
+
 if ( n > 0 ) {
 
    index = nint(floor((n - 1)*t));
@@ -76,6 +87,7 @@ if ( n > 0 ) {
       delta = (n - 1)*t - index;
       p = (1 - delta)*ordered_array[index] + delta*ordered_array[index + 1];
    }
+
 }
 
 return ( p );
@@ -110,6 +122,17 @@ int index;
 float delta; 
 float p = bad_data_float;
 
+// Range check
+if ( t < 0.0 || t > 1.0 ) {
+
+   mlog << Error << "\npercentile_f() -> "
+        << "requested percentile value (" << t
+        << ") must be between 0 and 1!\n\n";
+
+   exit ( 1 );
+
+}
+
 if ( n > 0 ) {
 
    index = nint(floor((n - 1)*t));

From 346c1bb78e86dd0552a284fa9be311a1d7adc5e8 Mon Sep 17 00:00:00 2001
From: John Halley Gotway <johnhg@ucar.edu>
Date: Wed, 16 Aug 2023 11:15:24 -0600
Subject: [PATCH 4/4] Per #2644, include vx_log.h

---
 src/basic/vx_math/ptile.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/basic/vx_math/ptile.cc b/src/basic/vx_math/ptile.cc
index 9ff068b8b1..9812403a84 100644
--- a/src/basic/vx_math/ptile.cc
+++ b/src/basic/vx_math/ptile.cc
@@ -23,6 +23,7 @@ using namespace std;
 #include "is_bad_data.h"
 
 #include "nint.h"
+#include "vx_log.h"
 
 
 ///////////////////////////////////////////////////////////////////////////////