Merge bitcoin/bitcoin#23418: Fix signed integer overflow in prioritisetransaction RPC

fa07f84e316171d60dd9941fb8db37e0a0de6654 Fix signed integer overflow in prioritisetransaction RPC (MarcoFalke)
fa52cf8e11b3af6e0a302d5d17aab6cea78899d5 refactor: Replace feeDelta by m_modified_fee (MarcoFalke)

Pull request description:

  Signed integer overflow is UB in theory, but not in practice. Still,
  it would be nice to avoid this UB to allow Bitcoin Core to be
  compiled with sanitizers such as `-ftrapv` or ubsan.

  It is impossible to predict when and if an overflow occurs, since
  the overflow caused by a prioritisetransaction RPC might only be
  later hit when descendant txs are added to the mempool.
  Since it is impossible to predict reliably, leave it up to the user
  to use the RPC endpoint responsibly, considering their mempool
  limits and usage patterns.

  Fixes: #20626
  Fixes: #20383
  Fixes: #19278
  Fixes: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=34146 / https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=47132

  ## Steps to reproduce

  Build the code without the changes in this pull.

  Make sure to pass the sanitizer flag:

  ```
  ./autogen.sh && ./configure --with-sanitizers=signed-integer-overflow && make clean && make -j $(nproc)
  ```

  ### Reproduce on RPC

  ```
  ./src/bitcoind -chain=regtest -noprinttoconsole &
  ./src/bitcoin-cli -chain=regtest prioritisetransaction 00000000deadbeef00000000deadbeef00000000deadbeef00000000deadbeef 0 9123456789123456789
  ./src/bitcoin-cli -chain=regtest prioritisetransaction 00000000deadbeef00000000deadbeef00000000deadbeef00000000deadbeef 0 9123456789123456789
  |> txmempool.cpp:920:15: runtime error: signed integer overflow: 9123456789123456789 + 9123456789123456789 cannot be represented in type 'long int'

  ./src/bitcoin-cli -chain=regtest stop
  ```

  ### By fuzzing

  ```
  wget https://github.com/bitcoin/bitcoin/files/8921302/clusterfuzz-testcase-minimized-validation_load_mempool-5599531390074880.bin.txt
  FUZZ=validation_load_mempool ./src/test/fuzz/fuzz ./clusterfuzz-testcase-minimized-validation_load_mempool-5599531390074880.bin.txt
  |> txmempool.cpp:920:15: runtime error: signed integer overflow: 7214801925397553184 + 2314885530818453536 cannot be represented in type 'long int'
  |> validation_load_mempool: succeeded against 1 files in 0s.

ACKs for top commit:
  vasild:
    ACK fa07f84e316171d60dd9941fb8db37e0a0de6654
  dunxen:
    ACK fa07f84
  LarryRuane:
    ACK fa07f84e316171d60dd9941fb8db37e0a0de6654

Tree-SHA512: 4a357950af55a49c9113da0a50c2e743c5b752f0514dd8d16cd92bfde2f77dd0ef56aa98452626df6f7f7a5b51d1227021f6bc94091201a179f0d488ee32a0df

0 files changed, 0 insertions, 0 deletions