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Fix find_nodes_in_area misbehaving with out-of-map coordinates (#11770)
This ensures that no overflows (side-effects) happen within the find_nodes_in_area function by limiting coordinates like done in the map generation code.
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sfan5 committed Nov 26, 2021
1 parent b905138 commit 87ab97d
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Showing 2 changed files with 33 additions and 16 deletions.
31 changes: 17 additions & 14 deletions src/script/lua_api/l_env.cpp
Expand Up @@ -880,6 +880,21 @@ int ModApiEnvMod::l_find_node_near(lua_State *L)
return 0;
}

static void checkArea(v3s16 &minp, v3s16 &maxp)
{
auto volume = VoxelArea(minp, maxp).getVolume();
// Volume limit equal to 8 default mapchunks, (80 * 2) ^ 3 = 4,096,000
if (volume > 4096000) {
throw LuaError("Area volume exceeds allowed value of 4096000");
}

// Clamp to map range to avoid problems
#define CLAMP(arg) core::clamp(arg, (s16)-MAX_MAP_GENERATION_LIMIT, (s16)MAX_MAP_GENERATION_LIMIT)
minp = v3s16(CLAMP(minp.X), CLAMP(minp.Y), CLAMP(minp.Z));
maxp = v3s16(CLAMP(maxp.X), CLAMP(maxp.Y), CLAMP(maxp.Z));
#undef CLAMP
}

// find_nodes_in_area(minp, maxp, nodenames, [grouped])
int ModApiEnvMod::l_find_nodes_in_area(lua_State *L)
{
Expand All @@ -899,13 +914,7 @@ int ModApiEnvMod::l_find_nodes_in_area(lua_State *L)
}
#endif

v3s16 cube = maxp - minp + 1;
// Volume limit equal to 8 default mapchunks, (80 * 2) ^ 3 = 4,096,000
if ((u64)cube.X * (u64)cube.Y * (u64)cube.Z > 4096000) {
luaL_error(L, "find_nodes_in_area(): area volume"
" exceeds allowed value of 4096000");
return 0;
}
checkArea(minp, maxp);

std::vector<content_t> filter;
collectNodeIds(L, 3, ndef, filter);
Expand Down Expand Up @@ -1010,13 +1019,7 @@ int ModApiEnvMod::l_find_nodes_in_area_under_air(lua_State *L)
}
#endif

v3s16 cube = maxp - minp + 1;
// Volume limit equal to 8 default mapchunks, (80 * 2) ^ 3 = 4,096,000
if ((u64)cube.X * (u64)cube.Y * (u64)cube.Z > 4096000) {
luaL_error(L, "find_nodes_in_area_under_air(): area volume"
" exceeds allowed value of 4096000");
return 0;
}
checkArea(minp, maxp);

std::vector<content_t> filter;
collectNodeIds(L, 3, ndef, filter);
Expand Down
18 changes: 16 additions & 2 deletions src/unittest/test_voxelarea.cpp
Expand Up @@ -30,6 +30,7 @@ class TestVoxelArea : public TestBase

void test_addarea();
void test_pad();
void test_extent();
void test_volume();
void test_contains_voxelarea();
void test_contains_point();
Expand Down Expand Up @@ -65,6 +66,7 @@ void TestVoxelArea::runTests(IGameDef *gamedef)
{
TEST(test_addarea);
TEST(test_pad);
TEST(test_extent);
TEST(test_volume);
TEST(test_contains_voxelarea);
TEST(test_contains_point);
Expand Down Expand Up @@ -113,10 +115,22 @@ void TestVoxelArea::test_pad()
UASSERT(v1.MaxEdge == v3s16(-47, -9347, 969));
}

void TestVoxelArea::test_extent()
{
VoxelArea v1(v3s16(-1337, -547, -789), v3s16(-147, 447, 669));
UASSERT(v1.getExtent() == v3s16(1191, 995, 1459));

VoxelArea v2(v3s16(32493, -32507, 32753), v3s16(32508, -32492, 32768));
UASSERT(v2.getExtent() == v3s16(16, 16, 16));
}

void TestVoxelArea::test_volume()
{
VoxelArea v1(v3s16(-1337, 447, -789), v3s16(-147, -9547, 669));
UASSERTEQ(s32, v1.getVolume(), -184657133);
VoxelArea v1(v3s16(-1337, -547, -789), v3s16(-147, 447, 669));
UASSERTEQ(s32, v1.getVolume(), 1728980655);

VoxelArea v2(v3s16(32493, -32507, 32753), v3s16(32508, -32492, 32768));
UASSERTEQ(s32, v2.getVolume(), 4096);
}

void TestVoxelArea::test_contains_voxelarea()
Expand Down

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