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GH-50522: [C++][Gandiva] fix heap overflow in aes_encrypt output sizing #50523

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GH-50522: [C++][Gandiva] fix heap overflow in aes_encrypt output sizing #50523

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b74f571
use the aes block size to size the aes_encrypt output buffer
Arawoof06 Jul 16, 2026
06d25b7
guard the aes output size against int32 overflow
Arawoof06 Oct 17, 2026
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36 changes: 24 additions & 12 deletions cpp/src/gandiva/gdv_function_stubs.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@

#include <boost/crc.hpp>
#include <cstdio>
#include <limits>
#include <sstream>
#include <string>
#include <vector>
Expand All @@ -44,6 +45,9 @@ extern "C" {

ARROW_SUPPRESS_MISSING_DECLARATIONS_WARNING

// AES operates on 16 byte blocks for every supported key length.
static constexpr int64_t kAesBlockSize = 16;

static char mask_array[256] = {
(char)0, (char)1, (char)2, (char)3, (char)4, (char)5, (char)6, (char)7,
(char)8, (char)9, (char)10, (char)11, (char)12, (char)13, (char)14, (char)15,
Expand Down Expand Up @@ -366,19 +370,23 @@ const char* gdv_fn_aes_encrypt(int64_t context, const char* data, int32_t data_l
return "";
}

int64_t kAesBlockSize = 0;
if (key_data_len == 16 || key_data_len == 24 || key_data_len == 32) {
kAesBlockSize = static_cast<int64_t>(key_data_len);
} else {
if (key_data_len != 16 && key_data_len != 24 && key_data_len != 32) {
std::ostringstream oss;
oss << "invalid key length: " << key_data_len;
gdv_fn_context_set_error_msg(context, oss.str().c_str());
*out_len = 0;
return nullptr;
}

*out_len =
static_cast<int32_t>(arrow::bit_util::RoundUpToPowerOf2(data_len, kAesBlockSize));
int64_t alloc_len =
arrow::bit_util::RoundUpToPowerOf2(data_len, kAesBlockSize) + kAesBlockSize;
if (ARROW_PREDICT_FALSE(alloc_len > std::numeric_limits<int32_t>::max())) {
gdv_fn_context_set_error_msg(context,
"AES_ENCRYPT: would overflow maximum output size");
*out_len = 0;
return nullptr;
}
*out_len = static_cast<int32_t>(alloc_len);
char* ret = reinterpret_cast<char*>(gdv_fn_context_arena_malloc(context, *out_len));
if (ret == nullptr) {
std::string err_msg = "AES_ENCRYPT: could not allocate memory for ciphertext output";
Expand Down Expand Up @@ -412,19 +420,23 @@ const char* gdv_fn_aes_decrypt(int64_t context, const char* data, int32_t data_l
return "";
}

int64_t kAesBlockSize = 0;
if (key_data_len == 16 || key_data_len == 24 || key_data_len == 32) {
kAesBlockSize = static_cast<int64_t>(key_data_len);
} else {
if (key_data_len != 16 && key_data_len != 24 && key_data_len != 32) {
std::ostringstream oss;
oss << "invalid key length: " << key_data_len;
gdv_fn_context_set_error_msg(context, oss.str().c_str());
*out_len = 0;
return nullptr;
}

*out_len =
static_cast<int32_t>(arrow::bit_util::RoundUpToPowerOf2(data_len, kAesBlockSize));
int64_t alloc_len =
arrow::bit_util::RoundUpToPowerOf2(data_len, kAesBlockSize) + kAesBlockSize;
if (ARROW_PREDICT_FALSE(alloc_len > std::numeric_limits<int32_t>::max())) {
gdv_fn_context_set_error_msg(context,
"AES_DECRYPT: would overflow maximum output size");
*out_len = 0;
return nullptr;
}
*out_len = static_cast<int32_t>(alloc_len);
char* ret = reinterpret_cast<char*>(gdv_fn_context_arena_malloc(context, *out_len));
if (ret == nullptr) {
std::string err_msg = "Could not allocate memory for returning aes decrypt plaintext";
Expand Down
62 changes: 62 additions & 0 deletions cpp/src/gandiva/gdv_function_stubs_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1621,4 +1621,66 @@ TEST(TestGdvFnStubs, TestAesEncryptDecryptValidation) {
EXPECT_THAT(ctx.get_error(), ::testing::HasSubstr("invalid key length"));
ctx.Reset();
}

TEST(TestGdvFnStubs, TestAesEncryptBlockAlignedInput) {
gandiva::ExecutionContext ctx;
std::string key16 = "12345678abcdefgh";
auto key16_len = static_cast<int32_t>(key16.length());
int64_t ctx_ptr = reinterpret_cast<int64_t>(&ctx);

// A block-aligned input still gets a whole block of padding appended, so the
// ciphertext is one block longer than the input. Encrypting twice from the same
// context makes an undersized output buffer observable, because the second
// ciphertext lands on top of the first one.
std::string first = "aaaaaaaaaaaaaaaa";
std::string second = "bbbbbbbbbbbbbbbb";
auto first_len = static_cast<int32_t>(first.length());
auto second_len = static_cast<int32_t>(second.length());

int32_t first_cipher_len = 0;
const char* first_cipher = gdv_fn_aes_encrypt(
ctx_ptr, first.c_str(), first_len, key16.c_str(), key16_len, &first_cipher_len);
ASSERT_FALSE(ctx.has_error());
EXPECT_EQ(first_cipher_len, first_len + 16);

int32_t second_cipher_len = 0;
gdv_fn_aes_encrypt(ctx_ptr, second.c_str(), second_len, key16.c_str(), key16_len,
&second_cipher_len);
ASSERT_FALSE(ctx.has_error());

int32_t decrypted_len = 0;
const char* decrypted = gdv_fn_aes_decrypt(ctx_ptr, first_cipher, first_cipher_len,
key16.c_str(), key16_len, &decrypted_len);
ASSERT_FALSE(ctx.has_error());
EXPECT_EQ(first, std::string(decrypted, decrypted_len));
}

TEST(TestGdvFnStubs, TestAesOutputSizeOverflow) {
gandiva::ExecutionContext ctx;
std::string key16 = "12345678abcdefgh";
auto key16_len = static_cast<int32_t>(key16.length());
int64_t ctx_ptr = reinterpret_cast<int64_t>(&ctx);
std::string data = "a";

// Rounding up and adding the padding block pushes these lengths past INT32_MAX.
// The size check runs before the input is read, so the short buffer is fine.
for (int32_t data_len :
{std::numeric_limits<int32_t>::max() - 15, std::numeric_limits<int32_t>::max()}) {
int32_t out_len = -1;
const char* ret = gdv_fn_aes_encrypt(ctx_ptr, data.c_str(), data_len, key16.c_str(),
key16_len, &out_len);
EXPECT_EQ(ret, nullptr);
EXPECT_EQ(out_len, 0);
EXPECT_THAT(ctx.get_error(), ::testing::HasSubstr("would overflow"));
ctx.Reset();

out_len = -1;
ret = gdv_fn_aes_decrypt(ctx_ptr, data.c_str(), data_len, key16.c_str(), key16_len,
&out_len);
EXPECT_EQ(ret, nullptr);
EXPECT_EQ(out_len, 0);
EXPECT_THAT(ctx.get_error(), ::testing::HasSubstr("would overflow"));
ctx.Reset();
}
}
} // namespace gandiva
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