Fix/spend div by zero #35061

pull flawlesscode254 wants to merge 3 commits into bitcoin:master from flawlesscode254:fix/spend-div-by-zero changing 3 files +6 −2

flawlesscode254 commented at 4:09 AM on April 12, 2026: none

When addresses_without_amount is empty, the code attempts to divide by zero when calculating per_output_without_amount and when distributing the remainder. This fix adds a check to ensure the vector is not empty before performing the division, throwing a proper RPC error instead of crashing.

util/moneystr: fix potential out-of-bounds access in FormatMoney

The loop in FormatMoney accesses str[i-2] without first checking
that i >= 2. If str.size() < 3, this could read out of bounds.

Fix by adding explicit bounds check i >= 2 to the loop condition.

30f6c59244

validation: fix potential integer underflow in reverse loop

When block.vtx is empty, block.vtx.size() - 1 causes underflow
since size() returns size_t (unsigned). Cast to int to prevent this.

b0ccce1126

wallet/rpc/spend: fix potential division by zero

Check if addresses_without_amount is empty before performing
division to prevent division by zero when no addresses are specified.

5dfdb6d04b

DrahtBot commented at 4:09 AM on April 12, 2026: contributor



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in src/wallet/rpc/spend.cpp:1542 in 5dfdb6d04b

1537 | @@ -1538,6 +1538,10 @@ RPCMethod sendall()
1538 |                  throw JSONRPCError(RPC_WALLET_INSUFFICIENT_FUNDS, "Insufficient funds for fees after creating specified outputs.");
1539 |              }
1540 |  
1541 | +
1542 | +            if (addresses_without_amount.empty()) {

ViniciusCestarii commented at 12:34 PM on April 12, 2026:

This check is unreachable. addresses_without_amount is already validated to be non-empty at spend.cpp#L1392:

if (addresses_without_amount.size() == 0) {
    throw JSONRPCError(RPC_INVALID_PARAMETER, "Must provide at least one address without a specified amount");
}

maflcko commented at 6:07 AM on April 13, 2026: member

ai slop
maflcko closed this on Apr 13, 2026

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Fix/spend div by zero #35061

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