od `--traditional` offset/label arithmetic overflows on a near-maximal offset (overflow-checks panic; release wraps)

[leeewee]

In --traditional mode, od accepts an explicit pseudo-address label. A label near u64::MAX makes the offset accumulator overflow: InputOffset::increase_position adds the bytes-read n to the running position/label with unchecked u64 arithmetic (self.byte_pos += n, self.label = Some(l + n)). With a label of 0xffffffffffffffff, the very first read overflows that add.

It panics only under overflow-checks (debug builds, or a release build compiled with -C overflow-checks=on).

$ printf '0123456789ABCDEF' | ./target/debug/od --traditional - 0 0xffffffffffffffff
thread 'main' panicked at src/uu/od/src/input_offset.rs:40:31:
attempt to add with overflow
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
$ echo $?
101

Root cause

// src/uu/od/src/input_offset.rs
/// Increase `byte_pos` and `label` if a label is used.
pub fn increase_position(&mut self, n: u64) {
    self.byte_pos += n;                 // unchecked
    if let Some(l) = self.label {
        self.label = Some(l + n);       // <- input_offset.rs:40:31, overflows when l ≈ u64::MAX
    }
}

label comes directly from the --traditional pseudo-address argument (0xffffffffffffffff here = u64::MAX), and byte_pos from the (also user-influenceable) starting offset. Adding the per-read byte count n with plain +/+= overflows.