[M-2] Unchecked try_into unwrap may panic

[this-vishalsingh]

Context: provekit/verifier/src/whir_r1cs.rs

Description

The verifier uses try_into().unwrap() on prover-controlled hint vectors to convert them into fixed-size arrays (e.g., [FieldElement; 3]). If a maliciously crafted proof provides hint vectors of incorrect length, these unwrap calls will panic, crashing the verifier.

Affected code paths:

• Dual-commitment mode: lines 100–103
• Single-commitment mode: lines 148–150

A malicious prover can exploit this to perform a denial-of-service attack by sending malformed proofs that trigger the unwrap panics.

• Impacted code

let whir_sums_1: ([FieldElement; 3], [FieldElement; 3]) = (sums_1.0.try_into().unwrap(), sums_1.1.try_into().unwrap());
...
let whir_sums: ([FieldElement; 3], [FieldElement; 3]) = (sums.0.try_into().unwrap(), sums.1.try_into().unwrap());

Recommendation

Replace try_into().unwrap() with fallible conversions that return an error (for example, using try_into().context(...) or ensure!) so that malformed proofs produce a controlled verification error rather than a panic.