An issue was discovered in the slice-deque crate before 0.2.0 for Rust. There is memory corruption in certain allocation cases.

Affected: crates.io: slice-deque

Affected versions of this crate entered a corrupted state if mem::size_of::<T>() % allocation_granularity() != 0 and a specific allocation pattern was used: sufficiently shifting the deque elements over the mirrored page boundary.

This allows an attacker that controls controls both element insertion and removal to corrupt the deque, such that reading elements from it would read bytes corresponding to other elements in the deque. (e.g. a read of T could read some bytes from one value and some bytes from an adjacent one, resulting in a T whose value representation is not meaningful). This is undefined behavior.

The flaw was corrected by using a pair of pointers to track the head and tail of the deque instead of a pair of indices. This pair of pointers are represented using a Rust slice.

Affected: crates.io: slice-deque

Affected versions of this crate did not properly update the head and tail of the deque when inserting and removing elements from the front if, before insertion or removal, the tail of the deque was in the mirrored memory region, and if, after insertion or removal, the head of the deque is exactly at the beginning of the mirrored memory region.

An attacker that controls both element insertion and removal into the deque could put it in a corrupted state. Once the deque enters such an state, its head and tail are corrupted, but in bounds of the allocated memory. This can result in partial reads and writes, reads of uninitialized memory, reads of memory containing previously dropped objects, etc. An attacker could exploit this to alter program execution.

The flaw was corrected by properly updating the head and tail of the deque in this case.