common: saturate marginal_feerate() instead of overflowing - #9365
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morehouse wants to merge 1 commit into
Open
common: saturate marginal_feerate() instead of overflowing#9365morehouse wants to merge 1 commit into
marginal_feerate() instead of overflowing#9365morehouse wants to merge 1 commit into
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marginal_feerate() computed current_feerate * 1.1 as a double and
converted the result back to u32. Since current_feerate is chosen by
the peer in open_channel or update_fee, they could choose an absurdly
high value that overflows u32 after the computation. UBSan reports:
common/fee_states.c:179:10: runtime error: 4.72446e+09 is outside the range of representable values of type 'unsigned int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior common/fee_states.c:179:10
Do the arithmetic with u64 and saturate at UINT32_MAX to avoid the
undefined behavior.
Found by fuzzing with smite.
Changelog-Fixed: JSON-RPC: `listpeerchannels` no longer derives `receivable_msat` from an overflowed fee estimate when the peer sets an absurd `feerate_per_kw`.
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marginal_feerate()computedcurrent_feerate * 1.1as a double and converted the result back to u32. Sincecurrent_feerateis chosen by the peer viaopen_channelorupdate_fee, they could choose an absurdly high value that overflows u32 after the computation. UBSan reports:Do the arithmetic with u64 and saturate at
UINT32_MAXto avoid the undefined behavior.Found by fuzzing with smite.