From c4b7675c93024245b4cfa258ef8b939d9737cd39 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Eduardo=20Leegwater=20Sim=C3=B5es?= Date: Sat, 10 Feb 2024 02:04:05 +0100 Subject: [PATCH] piecrust: one instance per contract function call Changes the instance reclamation code to allow for exactly one module instance per contract function call. This changes the way in which the node processes the state, leading to diverging state roots on erroring calls. Simplifies the instance code by using an atomic integer to construct an atomically reference counted pointer, which then gets shared with the environment. This fixes some bad dereferences occuring under certain circumstances. Resolves: #325 --- piecrust/CHANGELOG.md | 3 + piecrust/src/call_tree.rs | 11 +-- piecrust/src/imports.rs | 38 +++++----- piecrust/src/instance.rs | 80 +++++++++++++++------ piecrust/src/session.rs | 148 +++++++++++--------------------------- 5 files changed, 126 insertions(+), 154 deletions(-) diff --git a/piecrust/CHANGELOG.md b/piecrust/CHANGELOG.md index f88fff6f..52c5737b 100644 --- a/piecrust/CHANGELOG.md +++ b/piecrust/CHANGELOG.md @@ -13,10 +13,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0 ### Changed +- Change to have one instance per contract function call [#325] - Upgrade `dusk-wasmtime` to version `17` ### Fixed +- Fix bad dereferences in caused by instance reclamation [#325] - Fix overflow in gas limit calculation in inter-contract call ## [0.15.0] - 2024-01-24 @@ -357,6 +359,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0 [#234]: https://github.com/dusk-network/piecrust/pull/234 +[#325]: https://github.com/dusk-network/piecrust/issues/325 [#301]: https://github.com/dusk-network/piecrust/issues/313 [#301]: https://github.com/dusk-network/piecrust/issues/301 [#296]: https://github.com/dusk-network/piecrust/issues/296 diff --git a/piecrust/src/call_tree.rs b/piecrust/src/call_tree.rs index 669a4c3e..1f6c77d6 100644 --- a/piecrust/src/call_tree.rs +++ b/piecrust/src/call_tree.rs @@ -9,13 +9,16 @@ use std::mem; use piecrust_uplink::ContractId; +use crate::instance::WrappedInstance; + /// An element of the call tree. -#[derive(Debug, Clone, Copy)] +#[derive(Clone)] pub struct CallTreeElem { pub contract_id: ContractId, pub limit: u64, pub spent: u64, pub mem_len: usize, + pub instance: WrappedInstance, } /// The tree of contract calls. @@ -47,7 +50,7 @@ impl CallTree { pub(crate) fn move_up(&mut self, spent: u64) -> Option { self.0.map(|inner| unsafe { (*inner).elem.spent = spent; - let elem = (*inner).elem; + let elem = (*inner).elem.clone(); let parent = (*inner).parent; if parent.is_none() { @@ -63,7 +66,7 @@ impl CallTree { /// current element. pub(crate) fn move_up_prune(&mut self) -> Option { self.0.map(|inner| unsafe { - let elem = (*inner).elem; + let elem = (*inner).elem.clone(); let parent = (*inner).parent; if let Some(parent) = parent { @@ -98,7 +101,7 @@ impl CallTree { i += 1; } - current.map(|inner| unsafe { (*inner).elem }) + current.map(|inner| unsafe { (*inner).elem.clone() }) } /// Clears the call tree of all elements. diff --git a/piecrust/src/imports.rs b/piecrust/src/imports.rs index 51d6896c..36d350a9 100644 --- a/piecrust/src/imports.rs +++ b/piecrust/src/imports.rs @@ -138,12 +138,12 @@ pub(crate) fn hq( ) -> WasmtimeResult { let env = fenv.data_mut(); - let instance = env.self_instance(); + let mut instance = env.self_instance(); let name_len = name_len as usize; - check_ptr(instance, name_ofs, name_len)?; - check_arg(instance, arg_len)?; + check_ptr(&instance, name_ofs, name_len)?; + check_arg(&instance, arg_len)?; let name = instance.with_memory(|buf| { // performance: use a dedicated buffer here? @@ -163,11 +163,11 @@ pub(crate) fn hd( ) -> WasmtimeResult { let env = fenv.data_mut(); - let instance = env.self_instance(); + let mut instance = env.self_instance(); let name_len = name_len as usize; - check_ptr(instance, name_ofs, name_len)?; + check_ptr(&instance, name_ofs, name_len)?; let name = instance.with_memory(|buf| { // performance: use a dedicated buffer here? @@ -194,13 +194,13 @@ pub(crate) fn c( ) -> WasmtimeResult { let env = fenv.data_mut(); - let instance = env.self_instance(); + let mut instance = env.self_instance(); let name_len = name_len as usize; - check_ptr(instance, mod_id_ofs, CONTRACT_ID_BYTES)?; - check_ptr(instance, name_ofs, name_len)?; - check_arg(instance, arg_len)?; + check_ptr(&instance, mod_id_ofs, CONTRACT_ID_BYTES)?; + check_ptr(&instance, name_ofs, name_len)?; + check_arg(&instance, arg_len)?; let argbuf_ofs = instance.arg_buffer_offset(); @@ -225,9 +225,7 @@ pub(crate) fn c( let callee_stack_element = env .push_callstack(mod_id, callee_limit) .expect("pushing to the callstack should succeed"); - let callee = env - .instance(&callee_stack_element.contract_id) - .expect("callee instance should exist"); + let mut callee = callee_stack_element.instance; callee.snap().map_err(|err| Error::MemorySnapshotFailure { reason: None, @@ -242,7 +240,7 @@ pub(crate) fn c( let ret_len = callee .call(name, arg.len() as u32, callee_limit) .map_err(Error::normalize)?; - check_arg(callee, ret_len as u32)?; + check_arg(&callee, ret_len as u32)?; // copy back result callee.read_argument(&mut memory[argbuf_ofs..][..ret_len as usize]); @@ -291,8 +289,8 @@ pub(crate) fn emit( let topic_len = topic_len as usize; - check_ptr(instance, topic_ofs, topic_len)?; - check_arg(instance, arg_len)?; + check_ptr(&instance, topic_ofs, topic_len)?; + check_arg(&instance, arg_len)?; let data = instance.with_arg_buf(|buf| { let arg_len = arg_len as usize; @@ -327,7 +325,7 @@ fn feed(mut fenv: Caller, arg_len: u32) -> WasmtimeResult<()> { let env = fenv.data_mut(); let instance = env.self_instance(); - check_arg(instance, arg_len)?; + check_arg(&instance, arg_len)?; let data = instance.with_arg_buf(|buf| { let arg_len = arg_len as usize; @@ -342,7 +340,7 @@ fn hdebug(mut fenv: Caller, msg_len: u32) -> WasmtimeResult<()> { let env = fenv.data_mut(); let instance = env.self_instance(); - check_arg(instance, msg_len)?; + check_arg(&instance, msg_len)?; Ok(instance.with_arg_buf(|buf| { let slice = &buf[..msg_len as usize]; @@ -365,7 +363,7 @@ fn limit(fenv: Caller) -> u64 { fn spent(fenv: Caller) -> u64 { let env = fenv.data(); - let instance = env.self_instance(); + let mut instance = env.self_instance(); let limit = env.limit(); let remaining = instance.get_remaining_gas(); @@ -377,7 +375,7 @@ fn panic(fenv: Caller, arg_len: u32) -> WasmtimeResult<()> { let env = fenv.data(); let instance = env.self_instance(); - check_arg(instance, arg_len)?; + check_arg(&instance, arg_len)?; Ok(instance.with_arg_buf(|buf| { let slice = &buf[..arg_len as usize]; @@ -392,7 +390,7 @@ fn panic(fenv: Caller, arg_len: u32) -> WasmtimeResult<()> { } fn owner(fenv: Caller, mod_id_ofs: usize) -> WasmtimeResult { - check_ptr(fenv.data().self_instance(), mod_id_ofs, CONTRACT_ID_BYTES)?; + check_ptr(&fenv.data().self_instance(), mod_id_ofs, CONTRACT_ID_BYTES)?; let env = fenv.data(); diff --git a/piecrust/src/instance.rs b/piecrust/src/instance.rs index 8b60aa60..0f6df9c3 100644 --- a/piecrust/src/instance.rs +++ b/piecrust/src/instance.rs @@ -5,7 +5,9 @@ // Copyright (c) DUSK NETWORK. All rights reserved. use std::io; +use std::mem::MaybeUninit; use std::ops::{Deref, DerefMut}; +use std::sync::atomic::{AtomicUsize, Ordering}; use dusk_wasmtime::{Instance, Module, Mutability, Store, ValType}; use piecrust_uplink::{ContractId, Event, ARGBUF_LEN}; @@ -16,16 +18,45 @@ use crate::session::Session; use crate::store::Memory; use crate::Error; -pub struct WrappedInstance { - instance: Instance, - arg_buf_ofs: usize, - store: Store, - memory: Memory, +pub struct WrappedInstance(*mut WrappedInstanceInner); + +impl Clone for WrappedInstance { + fn clone(&self) -> Self { + unsafe { + (*self.0).count.fetch_add(1, Ordering::SeqCst); + Self(self.0) + } + } +} + +impl Drop for WrappedInstance { + fn drop(&mut self) { + if self.count.fetch_sub(1, Ordering::SeqCst) == 1 { + unsafe { + let _ = Box::from_raw(self.0); + } + } + } +} + +impl Deref for WrappedInstance { + type Target = WrappedInstanceInner; + + fn deref(&self) -> &Self::Target { + unsafe { &*self.0 } + } +} + +impl DerefMut for WrappedInstance { + fn deref_mut(&mut self) -> &mut Self::Target { + unsafe { &mut *self.0 } + } } pub(crate) struct Env { self_id: ContractId, session: Session, + instance: MaybeUninit, } impl Deref for Env { @@ -43,20 +74,8 @@ impl DerefMut for Env { } impl Env { - pub fn self_instance<'b>(&self) -> &'b mut WrappedInstance { - let stack_element = self - .session - .nth_from_top(0) - .expect("there should be at least one element in the call stack"); - self.instance(&stack_element.contract_id) - .expect("instance should exist") - } - - pub fn instance<'b>( - &self, - contract_id: &ContractId, - ) -> Option<&'b mut WrappedInstance> { - self.session.instance(contract_id) + pub fn self_instance(&self) -> WrappedInstance { + unsafe { self.instance.assume_init_ref().clone() } } pub fn limit(&self) -> u64 { @@ -94,6 +113,7 @@ impl WrappedInstance { let env = Env { self_id: contract_id, session, + instance: MaybeUninit::uninit(), }; let module = @@ -177,16 +197,32 @@ impl WrappedInstance { // A memory is no longer new after one instantiation memory.is_new = false; - let wrapped = WrappedInstance { + let inner = WrappedInstanceInner { store, instance, arg_buf_ofs, memory, + count: AtomicUsize::new(1), }; - Ok(wrapped) + let mut instance = WrappedInstance(Box::into_raw(Box::new(inner))); + let instance_clone = instance.clone(); + + instance.store.data_mut().instance = MaybeUninit::new(instance_clone); + + Ok(instance) } +} + +pub struct WrappedInstanceInner { + instance: Instance, + arg_buf_ofs: usize, + store: Store, + memory: Memory, + count: AtomicUsize, +} +impl WrappedInstanceInner { pub(crate) fn snap(&mut self) -> io::Result<()> { self.memory.snap()?; Ok(()) @@ -342,7 +378,7 @@ impl WrappedInstance { } fn map_call_err( - instance: &mut WrappedInstance, + instance: &mut WrappedInstanceInner, err: dusk_wasmtime::Error, ) -> Error { if instance.get_remaining_gas() == 0 { diff --git a/piecrust/src/session.rs b/piecrust/src/session.rs index 66970b58..e0946cbf 100644 --- a/piecrust/src/session.rs +++ b/piecrust/src/session.rs @@ -69,7 +69,7 @@ impl Drop for Session { if self.original { // ensure the stack is cleared and all instances are removed and // reclaimed on the drop of a session. - self.clear_stack_and_instances(); + self.clear_stack(); // SAFETY: this is safe since we guarantee that there is no aliasing // when a session drops. @@ -85,7 +85,6 @@ struct SessionInner { current: ContractId, call_tree: CallTree, - instances: BTreeMap, debug: Vec, data: SessionData, @@ -139,7 +138,6 @@ impl Session { let inner = SessionInner { current: ContractId::uninitialized(), call_tree: CallTree::new(), - instances: BTreeMap::new(), debug: vec![], data, contract_session, @@ -285,9 +283,9 @@ impl Session { .map_err(|err| PersistenceError(Arc::new(err)))?; let instantiate = || { - self.create_instance(contract_id)?; - let instance = - self.instance(&contract_id).expect("instance should exist"); + let mut stack_element = + self.push_callstack(contract_id, gas_limit)?; + let instance = &mut stack_element.instance; let has_init = instance.is_function_exported(INIT_METHOD); if has_init && arg.is_none() { @@ -499,26 +497,8 @@ impl Session { .map(|data| data.memory.current_len)) } - pub(crate) fn instance<'a>( - &self, - contract_id: &ContractId, - ) -> Option<&'a mut WrappedInstance> { - self.inner.instances.get(contract_id).map(|instance| { - // SAFETY: We guarantee that the instance exists since we're in - // control over if it is dropped with the session. - unsafe { &mut **instance } - }) - } - - fn clear_stack_and_instances(&mut self) { + fn clear_stack(&mut self) { self.inner.call_tree.clear(); - - while !self.inner.instances.is_empty() { - let (_, instance) = self.inner.instances.pop_first().unwrap(); - unsafe { - let _ = Box::from_raw(instance); - }; - } } /// Return the state root of the current state of the session. @@ -556,10 +536,24 @@ impl Session { feed.send(data).map_err(Error::FeedPulled) } - fn new_instance( + pub(crate) fn host_query( + &self, + name: &str, + buf: &mut [u8], + arg_len: u32, + ) -> Option { + self.inner.host_queries.call(name, buf, arg_len) + } + + pub(crate) fn nth_from_top(&self, n: usize) -> Option { + self.inner.call_tree.nth_parent(n) + } + + pub(crate) fn push_callstack( &mut self, contract_id: ContractId, - ) -> Result { + limit: u64, + ) -> Result { let store_data = self .inner .contract_session @@ -574,76 +568,22 @@ impl Session { )?; self.inner.current = contract_id; + let memory = store_data.memory; let instance = WrappedInstance::new( self.clone(), contract_id, &contract, - store_data.memory, + memory.clone(), )?; - Ok(instance) - } - - pub(crate) fn host_query( - &self, - name: &str, - buf: &mut [u8], - arg_len: u32, - ) -> Option { - self.inner.host_queries.call(name, buf, arg_len) - } - - pub(crate) fn nth_from_top(&self, n: usize) -> Option { - self.inner.call_tree.nth_parent(n) - } - - /// Creates a new instance of the given contract, returning its memory - /// length. - fn create_instance( - &mut self, - contract: ContractId, - ) -> Result { - let instance = self.new_instance(contract)?; - if self.inner.instances.get(&contract).is_some() { - panic!("Contract already in the stack: {contract:?}"); - } - - let mem_len = instance.mem_len(); - - let instance = Box::new(instance); - let instance = Box::leak(instance) as *mut WrappedInstance; - - self.inner.instances.insert(contract, instance); - Ok(mem_len) - } - - pub(crate) fn push_callstack( - &mut self, - contract_id: ContractId, - limit: u64, - ) -> Result { - let instance = self.instance(&contract_id); - - match instance { - Some(instance) => { - self.inner.call_tree.push(CallTreeElem { - contract_id, - limit, - spent: 0, - mem_len: instance.mem_len(), - }); - } - None => { - let mem_len = self.create_instance(contract_id)?; - self.inner.call_tree.push(CallTreeElem { - contract_id, - limit, - spent: 0, - mem_len, - }); - } - } + self.inner.call_tree.push(CallTreeElem { + contract_id, + limit, + spent: 0, + mem_len: instance.mem_len(), + instance, + }); Ok(self .inner @@ -662,11 +602,8 @@ impl Session { pub(crate) fn revert_callstack(&mut self) -> Result<(), std::io::Error> { for elem in self.inner.call_tree.iter() { - let instance = self - .instance(&elem.contract_id) - .expect("instance should exist"); - instance.revert()?; - instance.set_len(elem.mem_len); + elem.instance.clone().revert()?; + elem.instance.clone().set_len(elem.mem_len); } Ok(()) @@ -725,10 +662,8 @@ impl Session { fdata: Vec, limit: u64, ) -> Result<(Vec, u64, CallTree), Error> { - let stack_element = self.push_callstack(contract, limit)?; - let instance = self - .instance(&stack_element.contract_id) - .expect("instance should exist"); + let mut stack_element = self.push_callstack(contract, limit)?; + let instance = &mut stack_element.instance; instance .snap() @@ -748,7 +683,7 @@ impl Session { }; } self.move_up_prune_call_tree(); - self.clear_stack_and_instances(); + self.clear_stack(); err }) .map_err(Error::normalize)?; @@ -757,17 +692,14 @@ impl Session { let spent = limit - instance.get_remaining_gas(); for elem in self.inner.call_tree.iter() { - let instance = self - .instance(&elem.contract_id) - .expect("instance should exist"); - instance - .apply() - .map_err(|err| Error::MemorySnapshotFailure { + elem.instance.clone().apply().map_err(|err| { + Error::MemorySnapshotFailure { reason: None, io: Arc::new(err), - })?; + } + })?; } - self.clear_stack_and_instances(); + self.clear_stack(); let mut call_tree = CallTree::new(); mem::swap(&mut self.inner.call_tree, &mut call_tree);