Soundness: Creating GenericStringArray from ArrayData does not perform bound checks on reading offsets

[jorgecarleitao]

Equivalent to #773 for the GenericStringArray.

use arrow::array::*;
use arrow::buffer::*;
use arrow::datatypes::*;

fn main() {
    let data = ArrayData::new(
        DataType::Utf8,
        10,
        None,
        None,
        0,
        vec![
            Buffer::from_slice_ref(&[0i32, 1]),
            Buffer::from_slice_ref(&[0b00100100u8]),
        ],
        vec![],
    );
    let a = StringArray::from(data);
    let b = a.value(1);
    println!("{}", b);
}

error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
   --> /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/arith.rs:213:1
    |
213 | sub_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using uninitialized data, but this operation requires initialized memory
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
            
    = note: inside `<i32 as std::ops::Sub>::sub` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/arith.rs:206:45
    = note: inside `arrow::array::GenericStringArray::<i32>::value` at /home/azureuser/projects/arrow-rs/arrow/src/array/array_string.rs:121:17
note: inside `main` at arrow/examples/unsafe.rs:19:13
   --> arrow/examples/unsafe.rs:19:13
    |
19  |     let b = a.value(1);
    |             ^^^^^^^^^^
    = note: inside `<fn() as std::ops::FnOnce<()>>::call_once - shim(fn())` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:227:5
    = note: inside `std::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()>` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys_common/backtrace.rs:125:18
    = note: inside closure at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:63:18
    = note: inside `std::ops::function::impls::<impl std::ops::FnOnce<()> for &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>::call_once` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:259:13
    = note: inside `std::panicking::r#try::do_call::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:401:40
    = note: inside `std::panicking::r#try::<i32, &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:365:19
    = note: inside `std::panic::catch_unwind::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:434:14
    = note: inside closure at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:45:48
    = note: inside `std::panicking::r#try::do_call::<[closure@std::rt::lang_start_internal::{closure#2}], isize>` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:401:40
    = note: inside `std::panicking::r#try::<isize, [closure@std::rt::lang_start_internal::{closure#2}]>` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:365:19
    = note: inside `std::panic::catch_unwind::<[closure@std::rt::lang_start_internal::{closure#2}], isize>` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:434:14
    = note: inside `std::rt::lang_start_internal` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:45:20
    = note: inside `std::rt::lang_start::<()>` at /home/azureuser/.rustup/toolchains/nightly-2021-07-04-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:62:5
    = note: this error originates in the macro `sub_impl` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to previous error

[alamb]

Updating title of the ticket to make it clear this affects misusing the lower level APIs, as described in https://github.com/apache/arrow-rs/tree/master/arrow#safety

[alamb]

This is a specific case of the general issue described in #817, so closing this one as a duplicate in favor of the more general ticket.