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Fix heap buffer overflow #215

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Merged
etr merged 2 commits into from
Dec 11, 2020
Merged

Fix heap buffer overflow #215

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bcd12d3
Fix potential issue with heap buffer overflow.
etr Nov 22, 2020
bde590f
Added unit test to cover new codepath in unescaping
etr Nov 22, 2020
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12 changes: 7 additions & 5 deletions src/http_utils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <fstream>
#include <iomanip>
#include <iterator>
Expand Down Expand Up @@ -304,12 +305,13 @@ size_t http_unescape(std::string& val)
{
if (val.empty()) return 0;

int rpos = 0;
int wpos = 0;
unsigned int rpos = 0;
unsigned int wpos = 0;

unsigned int num;
unsigned int size = val.size();

while ('\0' != val[rpos])
while (rpos < size && val[rpos] != '\0')
{
switch (val[rpos])
{
Expand All @@ -319,8 +321,8 @@ size_t http_unescape(std::string& val)
rpos++;
break;
case '%':
if ( (1 == sscanf (val.substr(rpos + 1).c_str(), "%2x", &num)) ||
(1 == sscanf (val.substr(rpos + 1).c_str(), "%2X", &num))
if (size > rpos + 2 && ((1 == sscanf (val.substr(rpos + 1, 2).c_str(), "%2x", &num)) ||
(1 == sscanf (val.substr(rpos + 1, 2).c_str(), "%2X", &num)))
)
{
val[wpos] = (unsigned char) num;
Expand Down
18 changes: 17 additions & 1 deletion test/unit/http_utils_test.cpp
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Expand Up @@ -67,7 +67,7 @@ LT_BEGIN_AUTO_TEST(http_utils_suite, unescape)
LT_END_AUTO_TEST(unescape)

LT_BEGIN_AUTO_TEST(http_utils_suite, unescape_plus)
char* with_plus = (char*) malloc(6 * sizeof(char));
char* with_plus = (char*) malloc(4 * sizeof(char));
sprintf(with_plus, "%s", "A+B");
std::string string_with_plus = with_plus;
int expected_size = http::http_unescape(string_with_plus);
Expand All @@ -82,6 +82,22 @@ LT_BEGIN_AUTO_TEST(http_utils_suite, unescape_plus)
free(expected);
LT_END_AUTO_TEST(unescape_plus)

LT_BEGIN_AUTO_TEST(http_utils_suite, unescape_partial_marker)
char* with_marker = (char*) malloc(6 * sizeof(char));
sprintf(with_marker, "%s", "A+B%0");
std::string string_with_marker = with_marker;
int expected_size = http::http_unescape(string_with_marker);

char* expected = (char*) malloc(6 * sizeof(char));
sprintf(expected, "%s", "A B%0");

LT_CHECK_EQ(string_with_marker, string(expected));
LT_CHECK_EQ(expected_size, 5);

free(with_marker);
free(expected);
LT_END_AUTO_TEST(unescape_partial_marker)

LT_BEGIN_AUTO_TEST(http_utils_suite, tokenize_url)
string value = "test/this/url/here";
string expected_arr[] = { "test", "this", "url", "here" };
Expand Down