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grab bag of small UB fixes #2298

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merged 4 commits into from
Mar 12, 2024
Merged

grab bag of small UB fixes #2298

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c241ae5
guard against calling memcpy() with NULL src
spoonincode Mar 8, 2024
f2111db
avoid pointer arithmetic overflow
spoonincode Mar 8, 2024
a0b41fc
don't enable EOS VM OC's vm_limit when ASAN or UBSAN is enabled
spoonincode Mar 11, 2024
62e95b3
bump abieos, appbase, bn256 & eos-vm to their main HEAD w/ UB fixes
spoonincode Mar 11, 2024
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2 changes: 1 addition & 1 deletion libraries/appbase
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Submodule appbase updated 2 files
+2 −2 application_base.cpp
+11 −9 include/appbase/application_base.hpp
8 changes: 8 additions & 0 deletions libraries/chain/include/eosio/chain/webassembly/eos-vm-oc/config.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,10 @@

#include <sys/resource.h>

#ifndef __has_feature
#define __has_feature(x) 0
#endif

namespace eosio { namespace chain { namespace eosvmoc {

struct config {
Expand All @@ -20,7 +24,11 @@ struct config {
// libtester disables the limits in all tests, except enforces the limits
// in the tests in unittests/eosvmoc_limits_tests.cpp.
std::optional<rlim_t> cpu_limit {20u};
#if __has_feature(undefined_behavior_sanitizer) || __has_feature(address_sanitizer)
std::optional<rlim_t> vm_limit; // UBSAN & ASAN can add massive virtual memory usage; don't enforce vm limits when either of them are enabled
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Don't need this for tests to pass: OC in unit tests always has vm_limit disabled now (except for the one modified test case), and python integration tests never use OC. But I'd like to use OC + ASAN/UBSAN with nodeos. Such usage is probably "developer enough" where simply disabling this limit is safe when configured that way; i.e. won't trap unsuspecting users. Alternatively could guard this disablement behind EOSVMOC_ENABLE_DEVELOPER_OPTIONS but ultimately I want to remove that option.

#else
std::optional<rlim_t> vm_limit {512u*1024u*1024u};
#endif
std::optional<uint64_t> stack_size_limit {16u*1024u};
std::optional<size_t> generated_code_size_limit {16u*1024u*1024u};
};
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3 changes: 2 additions & 1 deletion libraries/chain/webassembly/runtimes/eos-vm-oc/compile_trampoline.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,8 @@ void run_compile(wrapped_fd&& response_sock, wrapped_fd&& wasm_code, uint64_t st

if(base_offset + data_segment.data.size() > initial_mem.size())
initial_mem.resize(base_offset + data_segment.data.size(), 0x00);
memcpy(initial_mem.data() + base_offset, data_segment.data.data(), data_segment.data.size());
if(data_segment.data.size())
memcpy(initial_mem.data() + base_offset, data_segment.data.data(), data_segment.data.size());
}

result_message.initdata_prologue_size = prologue.end() - prologue_it;
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2 changes: 1 addition & 1 deletion libraries/chain/webassembly/runtimes/eos-vm-oc/memory.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ memory::memory(uint64_t sliced_pages) {
uintptr_t* const intrinsic_jump_table = reinterpret_cast<uintptr_t* const>(zeropage_base - first_intrinsic_offset);
const intrinsic_map_t& intrinsics = get_intrinsic_map();
for(const auto& intrinsic : intrinsics)
intrinsic_jump_table[-intrinsic.second.ordinal] = (uintptr_t)intrinsic.second.function_ptr;
intrinsic_jump_table[-(int)intrinsic.second.ordinal] = (uintptr_t)intrinsic.second.function_ptr;
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This is an interesting one. The error here gets reported somewhat confusingly as addition of unsigned offset to 0x7aca262015f8 overflowed to 0x7aca26201570. I believe what is occurring is that ordinal is a size_t thus uint64_t, and negating it is still a uint64_t: now a really large uint64_t. But pointer arithmetic is defined on integer math; ptrdiff_t is a signed integer for example. So I think this is causing some sort of wrap around on a large signed integer. Casting ordinal to an int before the negation ensures it remains a small value int before pointer arithmetic. I'd be curious on other takes though.

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Should this use intptr_t (long int) instead of int?

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ordinal is the host function index over in,

leap/libraries/chain/include/eosio/chain/webassembly/eos-vm-oc/intrinsic_mapping.hpp

Lines 18 to 19 in 968a0fa

return detail::generate_table(
"eosvmoc_internal.unreachable",

so int will always be plenty large enough (we won't have 231 host functions). My initial impression of intptr_t is that its purpose/connotation isn't really for indexes in to an array.

I do wonder if ordinal should just be an int instead; I don't think it'd be too hard to change it.

}

memory::~memory() {
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2 changes: 1 addition & 1 deletion libraries/eos-vm
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Submodule eos-vm updated 1 files
+2 −1 include/eosio/vm/execution_context.hpp
2 changes: 1 addition & 1 deletion libraries/libfc/libraries/bn256
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Submodule bn256 updated 1 files
+6 −0 src/CMakeLists.txt
2 changes: 1 addition & 1 deletion tests/abieos
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Submodule abieos updated 2 files
+1 −1 include/eosio/chain_conversions.hpp
+4 −2 include/eosio/stream.hpp
10 changes: 10 additions & 0 deletions unittests/eosvmoc_limits_tests.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,8 @@ BOOST_AUTO_TEST_CASE( limits_not_enforced ) { try {
limit_not_violated_test(eosvmoc_config);
} FC_LOG_AND_RETHROW() }

// UBSAN & ASAN can add massive virtual memory usage; skip this test when either are enabled
#if !__has_feature(undefined_behavior_sanitizer) && !__has_feature(address_sanitizer)
// test VM limit are checked
BOOST_AUTO_TEST_CASE( vm_limit ) { try {
eosvmoc::config eosvmoc_config = make_eosvmoc_config_without_limits();
Expand All @@ -111,6 +113,14 @@ BOOST_AUTO_TEST_CASE( vm_limit ) { try {
limit_not_violated_test(eosvmoc_config);
} FC_LOG_AND_RETHROW() }

//make sure vm_limit is populated for a default constructed config (what nodeos will use)
BOOST_AUTO_TEST_CASE( check_config_default_vm_limit ) { try {
eosvmoc::config eosvmoc_config;

BOOST_REQUIRE(eosvmoc_config.vm_limit);
} FC_LOG_AND_RETHROW() }
#endif

// test stack size limit is checked
BOOST_AUTO_TEST_CASE( stack_limit ) { try {
eosvmoc::config eosvmoc_config = make_eosvmoc_config_without_limits();
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