GH-50472: [C++][Gandiva] fix integer overflow in mask output allocation

[Arawoof06]

Rationale for this change

mask_utf8_utf8_utf8_utf8 sizes its output arena buffer with std::max(upper_length, lower_length, num_length) * data_len in int32_t. The replacement lengths and the input length both come from the SQL mask arguments, so a large replacement combined with a large input wraps the multiply and yields a small max_length. The masking loop then writes each replacement past the undersized allocation. With data_len = 65536 and a 65537-byte replacement the true size is 4,295,032,832 which truncates to 65536, and the first masked character already overruns the buffer, crashing with SIGSEGV.

What changes are included in this PR?

Compute the size with arrow::internal::MultiplyWithOverflow and return an error when it overflows, the same guard repeat_utf8_int32, to_hex_binary, and the multibyte translate path already use.

Are these changes tested?

Yes. Added a case to TestGdvFnStubs.TestMask that passes a 64 KiB input with a 64 KiB+1 replacement; it crashes before the change and now returns an error with the fix.

Are there any user-facing changes?

mask on inputs whose masked size would exceed INT32_MAX now returns an error instead of crashing.

This PR contains a "Critical Fix". It fixes a heap buffer overflow (crash) reachable from the mask SQL function on large inputs.

• GitHub Issue: [C++][Gandiva] Integer overflow in mask output buffer size causes heap overflow #50472

[github-actions]

⚠️ GitHub issue #50472 has been automatically assigned in GitHub to PR creator.