From c731f8e5c05b8546a5aa35e3b0b8f027dc1f4009 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adolfo=20E=2E=20Garc=C3=ADa?= <adolfo.garcia.cr@gmail.com>
Date: Fri, 20 Oct 2017 18:05:33 -0600
Subject: [PATCH] Fix bug in Base32::decode and add bounds check

The bug that was fixed, was affecting how the number of bytes of decoded data was  calculated and thus, even though it didn't truncate the result, it was causing the array to be resized unnecessarily.
---
 src/core/Base32.cpp | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/core/Base32.cpp b/src/core/Base32.cpp
index 6fdecccd8..b76fd0293 100644
--- a/src/core/Base32.cpp
+++ b/src/core/Base32.cpp
@@ -83,7 +83,7 @@ QVariant Base32::decode(const QByteArray& encodedData)
 
     Q_ASSERT(encodedData.size() > 0);
     const int nQuanta = encodedData.size() / 8;
-    const int nBytes = (nQuanta - 1) * 5 + nSpecialBytes;
+    const int nBytes = nSpecialBytes > 0 ? (nQuanta - 1) * 5 + nSpecialBytes : nQuanta * 5;
 
     QByteArray data(nBytes, Qt::Uninitialized);
 
@@ -126,12 +126,17 @@ QVariant Base32::decode(const QByteArray& encodedData)
         const int offset = (nQuantumBytes - 1) * 8;
         quint64 mask = quint64(0xFF) << offset;
         for (int n = offset; n >= 0; n -= 8) {
-            char c = static_cast<char>((quantum & mask) >> n);
-            data[o++] = c;
-            mask >>= 8;
+            if (o < nBytes) {
+                data[o++] = static_cast<char>((quantum & mask) >> n);
+                mask >>= 8;
+            } else {
+              break;
+            }
         }
     }
 
+    Q_ASSERT(nBytes == o);
+
     return QVariant::fromValue(data);
 }
 
@@ -144,6 +149,7 @@ QByteArray Base32::encode(const QByteArray& data)
     const int nBits = data.size() * 8;
     const int rBits = nBits % 40; // in {0, 8, 16, 24, 32}
     const int nQuanta = nBits / 40 + (rBits > 0 ? 1 : 0);
+    const int nBytes = nQuanta * 8;
     QByteArray encodedData(nQuanta * 8, Qt::Uninitialized);
 
     int i = 0;
@@ -211,7 +217,8 @@ QByteArray Base32::encode(const QByteArray& data)
         }
     }
 
-    Q_ASSERT(encodedData.size() == o);
+    Q_ASSERT(data.size() == i);
+    Q_ASSERT(nBytes == o);
     return encodedData;
 }