[BUG] swap_remove index (is 4) should be < len (is 3) while running offchain workers

[shekohex]

Full stack-trace:

2022-01-12 16:30:42 Error running offchain workers at BlockId::Hash(0xb7e91242bc8f6114720f9f3eaaf2cb007103f86f33bd7e88ac855355d1bc9e0f): Application(Execution(RuntimePanicked("swap_remove index (is 4) should be < len (is 3)")))

====================

Version: 3.0.0-0eba6c4-x86_64-macos

   0: backtrace::backtrace::trace
   1: backtrace::capture::Backtrace::new
   2: sp_panic_handler::set::{{closure}}
   3: std::panicking::rust_panic_with_hook
             at /rustc/a77da2d454e6caa227a85b16410b95f93495e7e0/library/std/src/panicking.rs:610:17
   4: std::panicking::begin_panic_handler::{{closure}}
             at /rustc/a77da2d454e6caa227a85b16410b95f93495e7e0/library/std/src/panicking.rs:502:13
   5: std::sys_common::backtrace::__rust_end_short_backtrace
             at /rustc/a77da2d454e6caa227a85b16410b95f93495e7e0/library/std/src/sys_common/backtrace.rs:139:18
   6: rust_begin_unwind
             at /rustc/a77da2d454e6caa227a85b16410b95f93495e7e0/library/std/src/panicking.rs:498:5
   7: core::panicking::panic_fmt
             at /rustc/a77da2d454e6caa227a85b16410b95f93495e7e0/library/core/src/panicking.rs:107:14
   8: alloc::vec::Vec<T,A>::swap_remove::assert_failed
             at /rustc/a77da2d454e6caa227a85b16410b95f93495e7e0/library/alloc/src/vec/mod.rs:1300:13
   9: sp_runtime::offchain::storage::StorageValueRef::mutate
  10: pallet_dkg_proposal_handler::<impl pallet_dkg_proposal_handler::pallet::Pallet<T>>::get_next_offchain_signed_proposal
  11: pallet_dkg_proposal_handler::<impl pallet_dkg_proposal_handler::pallet::Pallet<T>>::submit_signed_proposal_onchain
  12: <(TupleElement0,TupleElement1) as frame_support::traits::misc::OffchainWorker<BlockNumber>>::offchain_worker
  13: frame_executive::Executive<System,Block,Context,UnsignedValidator,AllPalletsWithSystem,COnRuntimeUpgrade>::offchain_worker
  14: sp_offchain::runtime_decl_for_OffchainWorkerApi::offchain_worker_native_call_generator::{{closure}}
  15: std::thread::local::LocalKey<T>::with
  16: sc_executor::native_executor::WasmExecutor<H>::with_instance::{{closure}}
  17: sc_executor::wasm_runtime::RuntimeCache::with_instance
  18: <sc_executor::native_executor::NativeElseWasmExecutor<D> as sp_core::traits::CodeExecutor>::call
  19: sp_state_machine::execution::StateMachine<B,H,Exec>::execute_aux
  20: sp_state_machine::execution::StateMachine<B,H,Exec>::execute_using_consensus_failure_handler
  21: <sc_service::client::call_executor::LocalCallExecutor<Block,B,E> as sc_client_api::call_executor::CallExecutor<Block>>::contextual_call
  22: <sc_service::client::client::Client<B,E,Block,RA> as sp_api::CallApiAt<Block>>::call_api_at
  23: sp_offchain::runtime_decl_for_OffchainWorkerApi::offchain_worker_call_api_at
  24: <dkg_standalone_runtime::RuntimeApiImpl<__SR_API_BLOCK__,RuntimeApiImplCall> as sp_offchain::OffchainWorkerApi<__SR_API_BLOCK__>>::OffchainWorkerApi_offchain_worker_runtime_api_impl
  25: sp_offchain::OffchainWorkerApi::offchain_worker_with_context
  26: <F as threadpool::FnBox>::call_box
  27: std::sys_common::backtrace::__rust_begin_short_backtrace
  28: core::ops::function::FnOnce::call_once{{vtable.shim}}
  29: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
             at /rustc/a77da2d454e6caa227a85b16410b95f93495e7e0/library/alloc/src/boxed.rs:1694:9
      <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
             at /rustc/a77da2d454e6caa227a85b16410b95f93495e7e0/library/alloc/src/boxed.rs:1694:9
      std::sys::unix::thread::Thread::new::thread_start
             at /rustc/a77da2d454e6caa227a85b16410b95f93495e7e0/library/std/src/sys/unix/thread.rs:106:17
  30: __pthread_start


Thread 'offchain-worker' panicked at 'swap_remove index (is 4) should be < len (is 3)', library/alloc/src/vec/mod.rs:1300

This is a bug. Please report it at:

	support.anonymous.an

Full Debug data:

offchain-worker dkg_proposal_handler: Offchain signed proposals: [([AnchorUpdateSigned { data: [0, 0, 0, 0, 0, 0, 0, 0, 211, 12, 136, 57, 193, 20, 86, 9, 229, 100, 185, 134, 246, 103, 178, 115, 221, 203, 132, 150, 0, 0, 19, 138, 68, 52, 123, 169, 0, 0, 0, 0, 0, 0, 19, 137, 0, 0, 0, 0, 41, 14, 28, 191, 232, 139, 89, 149, 194, 218, 185, 239, 57, 237, 238, 49, 152, 128, 199, 203, 40, 43, 36, 29, 153, 110, 255, 232, 87, 51, 106, 67], signature: [208, 249, 87, 79, 26, 192, 146, 117, 91, 64, 201, 113, 170, 229, 206, 219, 177, 11, 243, 219, 86, 255, 112, 10, 121, 31, 128, 116, 16, 178, 44, 6, 89, 131, 151, 108, 140, 253, 93, 61, 43, 74, 214, 117, 58, 3, 135, 133, 34, 201, 156, 245, 111, 58, 169, 27, 40, 45, 140, 198, 245, 141, 225, 131, 1] }], 31), ([AnchorUpdateSigned { data: [0, 0, 0, 0, 0, 0, 0, 0, 211, 12, 136, 57, 193, 20, 86, 9, 229, 100, 185, 134, 246, 103, 178, 115, 221, 203, 132, 150, 0, 0, 19, 138, 68, 52, 123, 169, 0, 0, 0, 1, 0, 0, 19, 137, 0, 0, 0, 1, 41, 14, 28, 191, 232, 139, 89, 149, 194, 218, 185, 239, 57, 237, 238, 49, 152, 128, 199, 203, 40, 43, 36, 29, 153, 110, 255, 232, 87, 51, 106, 67], signature: [208, 249, 87, 79, 26, 192, 146, 117, 91, 64, 201, 113, 170, 229, 206, 219, 177, 11, 243, 219, 86, 255, 112, 10, 121, 31, 128, 116, 16, 178, 44, 6, 62, 153, 26, 30, 93, 18, 141, 211, 34, 198, 168, 121, 131, 232, 171, 39, 9, 78, 195, 170, 98, 160, 204, 197, 58, 172, 44, 215, 41, 154, 108, 191, 0] }], 31), ([AnchorUpdateSigned { data: [0, 0, 0, 0, 0, 0, 0, 0, 211, 12, 136, 57, 193, 20, 86, 9, 229, 100, 185, 134, 246, 103, 178, 115, 221, 203, 132, 150, 0, 0, 19, 138, 68, 52, 123, 169, 0, 0, 0, 0, 0, 0, 19, 137, 0, 0, 0, 0, 41, 14, 28, 191, 232, 139, 89, 149, 194, 218, 185, 239, 57, 237, 238, 49, 152, 128, 199, 203, 40, 43, 36, 29, 153, 110, 255, 232, 87, 51, 106, 67], signature: [208, 249, 87, 79, 26, 192, 146, 117, 91, 64, 201, 113, 170, 229, 206, 219, 177, 11, 243, 219, 86, 255, 112, 10, 121, 31, 128, 116, 16, 178, 44, 6, 89, 131, 151, 108, 140, 253, 93, 61, 43, 74, 214, 117, 58, 3, 135, 133, 34, 201, 156, 245, 111, 58, 169, 27, 40, 45, 140, 198, 245, 141, 225, 131, 1] }], 42), ([AnchorUpdateSigned { data: [0, 0, 0, 0, 0, 0, 0, 0, 211, 12, 136, 57, 193, 20, 86, 9, 229, 100, 185, 134, 246, 103, 178, 115, 221, 203, 132, 150, 0, 0, 19, 138, 68, 52, 123, 169, 0, 0, 0, 1, 0, 0, 19, 137, 0, 0, 0, 1, 41, 14, 28, 191, 232, 139, 89, 149, 194, 218, 185, 239, 57, 237, 238, 49, 152, 128, 199, 203, 40, 43, 36, 29, 153, 110, 255, 232, 87, 51, 106, 67], signature: [208, 249, 87, 79, 26, 192, 146, 117, 91, 64, 201, 113, 170, 229, 206, 219, 177, 11, 243, 219, 86, 255, 112, 10, 121, 31, 128, 116, 16, 178, 44, 6, 62, 153, 26, 30, 93, 18, 141, 211, 34, 198, 168, 121, 131, 232, 171, 39, 9, 78, 195, 170, 98, 160, 204, 197, 58, 172, 44, 215, 41, 154, 108, 191, 0] }], 42), ([AnchorUpdateSigned { data: [0, 0, 0, 0, 0, 0, 0, 0, 211, 12, 136, 57, 193, 20, 86, 9, 229, 100, 185, 134, 246, 103, 178, 115, 221, 203, 132, 150, 0, 0, 19, 138, 68, 52, 123, 169, 0, 0, 0, 0, 0, 0, 19, 137, 0, 0, 0, 0, 41, 14, 28, 191, 232, 139, 89, 149, 194, 218, 185, 239, 57, 237, 238, 49, 152, 128, 199, 203, 40, 43, 36, 29, 153, 110, 255, 232, 87, 51, 106, 67], signature: [208, 249, 87, 79, 26, 192, 146, 117, 91, 64, 201, 113, 170, 229, 206, 219, 177, 11, 243, 219, 86, 255, 112, 10, 121, 31, 128, 116, 16, 178, 44, 6, 89, 131, 151, 108, 140, 253, 93, 61, 43, 74, 214, 117, 58, 3, 135, 133, 34, 201, 156, 245, 111, 58, 169, 27, 40, 45, 140, 198, 245, 141, 225, 131, 1] }], 53), ([AnchorUpdateSigned { data: [0, 0, 0, 0, 0, 0, 0, 0, 211, 12, 136, 57, 193, 20, 86, 9, 229, 100, 185, 134, 246, 103, 178, 115, 221, 203, 132, 150, 0, 0, 19, 138, 68, 52, 123, 169, 0, 0, 0, 0, 0, 0, 19, 137, 0, 0, 0, 0, 41, 14, 28, 191, 232, 139, 89, 149, 194, 218, 185, 239, 57, 237, 238, 49, 152, 128, 199, 203, 40, 43, 36, 29, 153, 110, 255, 232, 87, 51, 106, 67], signature: [208, 249, 87, 79, 26, 192, 146, 117, 91, 64, 201, 113, 170, 229, 206, 219, 177, 11, 243, 219, 86, 255, 112, 10, 121, 31, 128, 116, 16, 178, 44, 6, 89, 131, 151, 108, 140, 253, 93, 61, 43, 74, 214, 117, 58, 3, 135, 133, 34, 201, 156, 245, 111, 58, 169, 27, 40, 45, 140, 198, 245, 141, 225, 131, 1] }], 64), ([AnchorUpdateSigned { data: [0, 0, 0, 0, 0, 0, 0, 0, 211, 12, 136, 57, 193, 20, 86, 9, 229, 100, 185, 134, 246, 103, 178, 115, 221, 203, 132, 150, 0, 0, 19, 138, 68, 52, 123, 169, 0, 0, 0, 0, 0, 0, 19, 137, 0, 0, 0, 0, 41, 14, 28, 191, 232, 139, 89, 149, 194, 218, 185, 239, 57, 237, 238, 49, 152, 128, 199, 203, 40, 43, 36, 29, 153, 110, 255, 232, 87, 51, 106, 67], signature: [208, 249, 87, 79, 26, 192, 146, 117, 91, 64, 201, 113, 170, 229, 206, 219, 177, 11, 243, 219, 86, 255, 112, 10, 121, 31, 128, 116, 16, 178, 44, 6, 89, 131, 151, 108, 140, 253, 93, 61, 43, 74, 214, 117, 58, 3, 135, 133, 34, 201, 156, 245, 111, 58, 169, 27, 40, 45, 140, 198, 245, 141, 225, 131, 1] }], 75)]
2022-01-12 16:30:42.107 DEBUG      offchain-worker dkg_proposal_handler: Offchain signed proposals left: 7

To trigger this bug, I guess you have to add a lot of unsigned proposals really quickly to the dkg system, and it triggers this error when it try to submit the signed proposals back on-chain.