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Add limit parameter to decompressZlib

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This can prevent untrusted data, such as sent over the network,
from consuming all memory with a specially crafted payload.
This commit is contained in:
Ben Deutsch 2018-01-30 22:12:40 +01:00 • committed by sfan5
parent 1116918dbb
commit 2b3490db1f
3 changed files with 81 additions and 4 deletions
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63
src/unittest/test_compression.cpp
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@ -37,6 +37,8 @@ public:
void testRLECompression();
void testZlibCompression();
void testZlibLargeData();
void testZlibLimit();
void _testZlibLimit(u32 size, u32 limit);
};
static TestCompression g_test_instance;
@ -46,6 +48,7 @@ void TestCompression::runTests(IGameDef *gamedef)
TEST(testRLECompression);
TEST(testZlibCompression);
TEST(testZlibLargeData);
TEST(testZlibLimit);
}
////////////////////////////////////////////////////////////////////////////////
@ -170,3 +173,63 @@ void TestCompression::testZlibLargeData()
i, str_decompressed[i], i, data_in[i]);
}
}
void TestCompression::testZlibLimit()
{
// edge cases
_testZlibLimit(1024, 1023);
_testZlibLimit(1024, 1024);
_testZlibLimit(1024, 1025);
// test around buffer borders
u32 bufsize = 16384; // as in implementation
for (int s = -1; s <= 1; s++)
{
for (int l = -1; l <= 1; l++)
{
_testZlibLimit(bufsize + s, bufsize + l);
}
}
// span multiple buffers
_testZlibLimit(35000, 22000);
_testZlibLimit(22000, 35000);
}
void TestCompression::_testZlibLimit(u32 size, u32 limit)
{
infostream << "Test: Testing zlib wrappers with a decompression "
"memory limit of " << limit << std::endl;
infostream << "Test: Input size of compressZlib for limit is "
<< size << std::endl;
// how much data we expect to get
u32 expected = size < limit ? size : limit;
// create recognizable data
std::string data_in;
data_in.resize(size);
for (u32 i = 0; i < size; i++)
data_in[i] = (u8)(i % 256);
std::ostringstream os_compressed(std::ios::binary);
compressZlib(data_in, os_compressed);
infostream << "Test: Output size of compressZlib for limit is "
<< os_compressed.str().size()<<std::endl;
std::istringstream is_compressed(os_compressed.str(), std::ios::binary);
std::ostringstream os_decompressed(std::ios::binary);
decompressZlib(is_compressed, os_decompressed, limit);
infostream << "Test: Output size of decompressZlib with limit is "
<< os_decompressed.str().size() << std::endl;
std::string str_decompressed = os_decompressed.str();
UASSERTEQ(size_t, str_decompressed.size(), expected);
for (u32 i = 0; i < size && i < str_decompressed.size(); i++) {
UTEST(str_decompressed[i] == data_in[i],
"index out[%i]=%i differs from in[%i]=%i",
i, str_decompressed[i], i, data_in[i]);
}
}