Affected versions of this crate would call Vec::set_len on an uninitialized vector with user-provided type parameter, in an interface of the HDR image format decoder. They would then also call other code that could panic before initializing all instances.

This could run Drop implementations on uninitialized types, equivalent to use-after-free, and allow an attacker arbitrary code execution.

Two different fixes were applied. It is possible to conserve the interface by ensuring proper initialization before calling Vec::set_len. Drop is no longer called in case of panic, though.

Starting from version 0.22, a breaking change to the interface requires callers to pre-allocate the output buffer and pass a mutable slice instead, avoiding all unsafe code.

Given the function transpose::transpose:

fn transpose<T: Copy>(input: &[T], output: &mut [T], input_width: usize, input_height: usize)

The safety check input_width * input_height == output.len() can fail due to input_width * input_height overflowing in such a way that it equals output.len(). As a result of failing the safety check, memory past the end of output is written to. This only occurs in release mode since * panics on overflow in debug mode.

Exploiting this issue requires the caller to pass input_width and input_height arguments such that multiplying them overflows, and the overflown result equals the lengths of input and output slices.