fix!: defensive ghost row constraints in bc_hashing pil #19481
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BEGIN_COMMIT_OVERRIDE feat(avm security): add static check for isolated/unused columns (#19489) feat(avm): use noop calldata hasher in fast sim (#19495) chore(avm): rename indirect -> addressing mode (#19491) chore(avm): small cursor optimizations chore(avm):! rename indirect -> addressing mode (PIL) (#19493) fix(avm): constraint when unwinding empty call stack (#19485) feat(avm): Fuzz debug log and refactor env getter (#19494) fix!: ecc add predicate completeness bug (#19471) chore(avm): callstackmetadatacollector clarifications (#19490) chore: sanity assert in execution for bytecode id (#19486) fix!: sstore allowed injection of malicious write rows (#19470) fix!: defensive ghost row constraints in bc_hashing pil (#19481) fix(avm): fix execution::mov for mac? (#19507) chore(avm)!: resolve execution TODOs (#19501) fix!: multiple traces had ghost row injection vulnerabilities (#19480) fix(avm): defensively copy MemoryValues (#19512) feat: align TS and BB log levels (#19518) END_COMMIT_OVERRIDE
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Summary
Adds defensive constraints to
bc_hashing.pilto prevent ghost row injection attacks on the#[GET_PACKED_FIELD_1]and#[GET_PACKED_FIELD_2]permutations.The vulnerability pattern: When
sel=0(gadget inactive), the sub-selectorssel_not_padding_1andsel_not_padding_2were only boolean-constrained, not forced to 0. A malicious prover could set these to 1 on ghost rows to fire the permutations intobc_decomposition.The fix: Add constraints that force these selectors to 0 when
sel=0:Note: This is a defensive fix. The destination trace (bc_decomposition) already has sel_packed * (1 - sel) = 0 which would block ghost destination rows, making the attack non-exploitable in practice.
Test Plan