From cd98afdd7bdc2c3f2e1a5d67089fa924035aa27c Mon Sep 17 00:00:00 2001
From: Andrew Gaul <andrew@gaul.org>
Date: Tue, 31 Aug 2021 00:15:47 +0900
Subject: [PATCH] Do not NUL terminate base64 decoded output (#1752)

This is binary data and must use the explicit length.
---
 src/string_util.cpp      |  3 +--
 src/test_string_util.cpp | 24 ++++++++++++++++++------
 src/test_util.h          | 12 ++++++++++++
 3 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/src/string_util.cpp b/src/string_util.cpp
index ee4ddf4..97fa601 100644
--- a/src/string_util.cpp
+++ b/src/string_util.cpp
@@ -438,7 +438,7 @@ unsigned char* s3fs_decode64(const char* input, size_t* plength)
     if(!input || 0 == strlen(input) || !plength){
         return NULL;
     }
-    result = new unsigned char[strlen(input) / 4 * 3 + 1];
+    result = new unsigned char[strlen(input) / 4 * 3];
 
     unsigned char parts[4];
     size_t input_len = strlen(input);
@@ -460,7 +460,6 @@ unsigned char* s3fs_decode64(const char* input, size_t* plength)
         }
         result[wpos++] = ((parts[2] << 6) & 0xc0) | (parts[3] & 0x3f);
     }
-    result[wpos] = '\0';
     *plength = wpos;
     return result;
 }
diff --git a/src/test_string_util.cpp b/src/test_string_util.cpp
index 7f5c442..22e52c0 100644
--- a/src/test_string_util.cpp
+++ b/src/test_string_util.cpp
@@ -64,23 +64,35 @@ void test_trim()
 
 void test_base64()
 {
+    unsigned char *buf;
     size_t len;
+
     ASSERT_STREQUALS(s3fs_base64(NULL, 0), NULL);
-    ASSERT_STREQUALS(reinterpret_cast<const char *>(s3fs_decode64(NULL, &len)), NULL);
+    buf = s3fs_decode64(NULL, &len);
+    ASSERT_BUFEQUALS(reinterpret_cast<const char *>(buf), len, NULL, 0);
+
     ASSERT_STREQUALS(s3fs_base64(reinterpret_cast<const unsigned char *>(""), 0), NULL);
-    ASSERT_STREQUALS(reinterpret_cast<const char *>(s3fs_decode64("", &len)), NULL);
+    buf = s3fs_decode64("", &len);
+    ASSERT_BUFEQUALS(reinterpret_cast<const char *>(buf), len, NULL, 0);
 
     ASSERT_STREQUALS(s3fs_base64(reinterpret_cast<const unsigned char *>("1"), 1), "MQ==");
-    ASSERT_STREQUALS(reinterpret_cast<const char *>(s3fs_decode64("MQ==", &len)), "1");
+    buf = s3fs_decode64("MQ==", &len);
+    ASSERT_BUFEQUALS(reinterpret_cast<const char *>(buf), len, "1", 1);
     ASSERT_EQUALS(len, static_cast<size_t>(1));
+
     ASSERT_STREQUALS(s3fs_base64(reinterpret_cast<const unsigned char *>("12"), 2), "MTI=");
-    ASSERT_STREQUALS(reinterpret_cast<const char *>(s3fs_decode64("MTI=", &len)), "12");
+    buf = s3fs_decode64("MTI=", &len);
+    ASSERT_BUFEQUALS(reinterpret_cast<const char *>(buf), len, "12", 2);
     ASSERT_EQUALS(len, static_cast<size_t>(2));
+
     ASSERT_STREQUALS(s3fs_base64(reinterpret_cast<const unsigned char *>("123"), 3), "MTIz");
-    ASSERT_STREQUALS(reinterpret_cast<const char *>(s3fs_decode64("MTIz", &len)), "123");
+    buf = s3fs_decode64("MTIz", &len);
+    ASSERT_BUFEQUALS(reinterpret_cast<const char *>(buf), len, "123", 3);
     ASSERT_EQUALS(len, static_cast<size_t>(3));
+
     ASSERT_STREQUALS(s3fs_base64(reinterpret_cast<const unsigned char *>("1234"), 4), "MTIzNA==");
-    ASSERT_STREQUALS(reinterpret_cast<const char *>(s3fs_decode64("MTIzNA==", &len)), "1234");
+    buf = s3fs_decode64("MTIzNA==", &len);
+    ASSERT_BUFEQUALS(reinterpret_cast<const char *>(buf), len, "1234", 4);
     ASSERT_EQUALS(len, static_cast<size_t>(4));
 
     // TODO: invalid input
diff --git a/src/test_util.h b/src/test_util.h
index b3b20c9..8c13bfc 100644
--- a/src/test_util.h
+++ b/src/test_util.h
@@ -76,11 +76,23 @@ void assert_strequals(const char *x, const char *y, const char *file, int line)
   }
 }
 
+void assert_bufequals(const char *x, size_t len1, const char *y, size_t len2, const char *file, int line)
+{
+    if(x == NULL && y == NULL){
+        return;
+    // cppcheck-suppress nullPointerRedundantCheck
+    } else if(x == NULL || y == NULL || len1 != len2 || memcmp(x, y, len1) != 0){
+        std::cerr << (x ? std::string(x, len1) : "null") << " != " << (y ? std::string(y, len2) : "null") << " at " << file << ":" << line << std::endl;
+        std::exit(1);
+    }
+}
+
 #define ASSERT_TRUE(x)          assert_equals((x), true, __FILE__, __LINE__)
 #define ASSERT_FALSE(x)         assert_equals((x), false, __FILE__, __LINE__)
 #define ASSERT_EQUALS(x, y)     assert_equals((x), (y), __FILE__, __LINE__)
 #define ASSERT_NEQUALS(x, y)    assert_nequals((x), (y), __FILE__, __LINE__)
 #define ASSERT_STREQUALS(x, y)  assert_strequals((x), (y), __FILE__, __LINE__)
+#define ASSERT_BUFEQUALS(x, len1, y, len2) assert_bufequals((x), (len1), (y), (len2), __FILE__, __LINE__)
 
 #endif // S3FS_TEST_UTIL_H_