58 avoid panic error (#63)

* Add avoid-panic-error detector with test cases

.github/workflows/test-detectors.yml

@@ -98,6 +98,7 @@ jobs:
         test:
           [
             "avoid-core-mem-forget",
+            "avoid-panic-error",
             "divide-before-multiply",
             "insufficiently-random-values",
             "overflow-check",

detectors/avoid-panic-error/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "avoid-panic-error"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+clippy_utils = { workspace = true }
+dylint_linting = { workspace = true }
+if_chain = { workspace = true }
+
+scout-audit-internal = { workspace = true }
+
+[dev-dependencies]
+dylint_testing = { workspace = true }
+
+[package.metadata.rust-analyzer]
+rustc_private = true

detectors/avoid-panic-error/src/lib.rs

@@ -0,0 +1,187 @@
+#![feature(rustc_private)]
+#![warn(unused_extern_crates)]
+
+extern crate rustc_ast;
+extern crate rustc_span;
+
+use clippy_utils::sym;
+use if_chain::if_chain;
+use rustc_ast::{
+    ptr::P,
+    token::{LitKind, TokenKind},
+    tokenstream::{TokenStream, TokenTree},
+    AttrArgs, AttrKind, Expr, ExprKind, Item, MacCall, StmtKind,
+};
+use rustc_lint::{EarlyContext, EarlyLintPass};
+use rustc_span::{sym, Span};
+use scout_audit_internal::Detector;
+
+dylint_linting::impl_pre_expansion_lint! {
+    /// ### What it does
+    /// The panic! macro is used to stop execution when a condition is not met.
+    /// This is useful for testing and prototyping, but should be avoided in production code
+    ///
+    /// ### Why is this bad?
+    /// The usage of panic! is not recommended because it will stop the execution of the caller contract.
+    ///
+    /// ### Known problems
+    /// While this linter detects explicit calls to panic!, there are some ways to raise a panic such as unwrap() or expect().
+    ///
+    /// ### Example
+    /// ```rust
+    /// pub fn add(env: Env, value: u32) -> u32 {
+    ///     let storage = env.storage().instance();
+    ///     let mut count: u32 = storage.get(&COUNTER).unwrap_or(0);
+    ///     match count.checked_add(value) {
+    ///         Some(value) => count = value,
+    ///         None => panic!("Overflow error"),
+    ///     }
+    ///     storage.set(&COUNTER, &count);
+    ///     storage.extend_ttl(100, 100);
+    ///     count
+    /// }
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// pub fn add(env: Env, value: u32) -> Result<u32, Error> {
+    ///     let storage = env.storage().instance();
+    ///     let mut count: u32 = storage.get(&COUNTER).unwrap_or(0);
+    ///     match count.checked_add(value) {
+    ///         Some(value) => count = value,
+    ///         None => return Err(Error::OverflowError),
+    ///     }
+    ///     storage.set(&COUNTER, &count);
+    ///     storage.extend_ttl(100, 100);
+    ///     Ok(count)
+    /// }
+    /// ```
+    pub AVOID_PANIC_ERROR,
+    Warn,
+    Detector::AvoidPanicError.get_lint_message(),
+    AvoidPanicError::default()
+}
+
+#[derive(Default)]
+pub struct AvoidPanicError {
+    in_test_span: Option<Span>,
+}
+
+impl EarlyLintPass for AvoidPanicError {
+    fn check_item(&mut self, _cx: &EarlyContext, item: &Item) {
+        match (is_test_item(item), self.in_test_span) {
+            (true, None) => self.in_test_span = Some(item.span),
+            (true, Some(test_span)) => {
+                if !test_span.contains(item.span) {
+                    self.in_test_span = Some(item.span);
+                }
+            }
+            (false, None) => {}
+            (false, Some(test_span)) => {
+                if !test_span.contains(item.span) {
+                    self.in_test_span = None;
+                }
+            }
+        };
+    }
+
+    fn check_stmt(&mut self, cx: &EarlyContext<'_>, stmt: &rustc_ast::Stmt) {
+        if_chain! {
+            if !self.in_test_item();
+            if let StmtKind::MacCall(mac) = &stmt.kind;
+            then {
+                check_macro_call(cx, stmt.span, &mac.mac)
+            }
+        }
+    }
+
+    fn check_expr(&mut self, cx: &EarlyContext, expr: &Expr) {
+        if_chain! {
+            if !self.in_test_item();
+            if let ExprKind::MacCall(mac) = &expr.kind;
+            then {
+                check_macro_call(cx, expr.span, mac)
+            }
+        }
+    }
+}
+
+fn check_macro_call(cx: &EarlyContext, span: Span, mac: &P<MacCall>) {
+    if_chain! {
+        if mac.path == sym!(panic);
+        if let [TokenTree::Token(token, _)] = mac
+            .args
+            .tokens
+            .clone()
+            .trees()
+            .collect::<Vec<_>>()
+            .as_slice();
+        if let TokenKind::Literal(lit) = token.kind;
+        if lit.kind == LitKind::Str;
+        then {
+            Detector::AvoidPanicError.span_lint_and_help(
+                cx,
+                AVOID_PANIC_ERROR,
+                span,
+                &format!("You could use instead an Error enum and then 'return Err(Error::{})'", capitalize_err_msg(lit.symbol.as_str()).replace(' ', "")),
+            );
+        }
+    }
+}
+
+fn is_test_item(item: &Item) -> bool {
+    item.attrs.iter().any(|attr| {
+        // Find #[cfg(all(test, feature = "e2e-tests"))]
+        if_chain!(
+            if let AttrKind::Normal(normal) = &attr.kind;
+            if let AttrArgs::Delimited(delim_args) = &normal.item.args;
+            if is_test_token_present(&delim_args.tokens);
+            then {
+                return true;
+            }
+        );
+
+        // Find unit or integration tests
+        if attr.has_name(sym::test) {
+            return true;
+        }
+
+        if_chain! {
+            if attr.has_name(sym::cfg);
+            if let Some(items) = attr.meta_item_list();
+            if let [item] = items.as_slice();
+            if let Some(feature_item) = item.meta_item();
+            if feature_item.has_name(sym::test);
+            then {
+                return true;
+            }
+        }
+
+        false
+    })
+}
+
+impl AvoidPanicError {
+    fn in_test_item(&self) -> bool {
+        self.in_test_span.is_some()
+    }
+}
+
+fn capitalize_err_msg(s: &str) -> String {
+    s.split_whitespace()
+        .map(|word| {
+            let mut chars = word.chars();
+            match chars.next() {
+                None => String::new(),
+                Some(f) => f.to_uppercase().collect::<String>() + chars.as_str(),
+            }
+        })
+        .collect::<Vec<String>>()
+        .join(" ")
+}
+
+fn is_test_token_present(token_stream: &TokenStream) -> bool {
+    token_stream.trees().any(|tree| match tree {
+        TokenTree::Token(token, _) => token.is_ident_named(sym::test),
+        TokenTree::Delimited(_, _, token_stream) => is_test_token_present(token_stream),
+    })
+}

scout-audit-internal/src/detector.rs

@@ -27,6 +27,7 @@ use strum::{Display, EnumIter};
 #[strum(serialize_all = "kebab-case")]
 pub enum Detector {
     AvoidCoreMemForget,
+    AvoidPanicError,
     DivideBeforeMultiply,
     InsufficientlyRandomValues,
     OverflowCheck,
@@ -41,8 +42,8 @@ impl Detector {
     pub const fn get_lint_message(&self) -> &'static str {
         match self {
             Detector::AvoidCoreMemForget => AVOID_CORE_MEM_FORGET_LINT_MESSAGE,
+            Detector::AvoidPanicError => AVOID_PANIC_ERROR_LINT_MESSAGE,
             Detector::InsufficientlyRandomValues => INSUFFICIENTLY_RANDOM_VALUES_LINT_MESSAGE,
-
             Detector::DivideBeforeMultiply => DIVIDE_BEFORE_MULTIPLY_LINT_MESSAGE,
             Detector::OverflowCheck => OVERFLOW_CHECK_LINT_MESSAGE,
             Detector::SetContractStorage => SET_CONTRACT_STORAGE_LINT_MESSAGE,

scout-audit-internal/src/detector/lint_message.rs

@@ -1,8 +1,8 @@
 pub const AVOID_CORE_MEM_FORGET_LINT_MESSAGE: &str =
     "Use the `let _ = ...` pattern or `.drop()` method to forget the value";
+pub const AVOID_PANIC_ERROR_LINT_MESSAGE: &str = "The panic! macro is used to stop execution when a condition is not met. Even when this does not break the execution of the contract, it is recommended to use Result instead of panic! because it will stop the execution of the caller contract";
 pub const INSUFFICIENTLY_RANDOM_VALUES_LINT_MESSAGE: &str =
     "Use env.prng() to generate random numbers, and remember that all random numbers are under the control of validators";
-
 pub const DIVIDE_BEFORE_MULTIPLY_LINT_MESSAGE: &str =
     "Division before multiplication might result in a loss of precision";
 pub const OVERFLOW_CHECK_LINT_MESSAGE: &str = "Use `overflow-checks = true` in Cargo.toml profile";

test-cases/avoid-panic-error/avoid-panic-error-1/remediated-example/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "avoid-panic-error-remediated-1"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+soroban-sdk = { version = "=20.0.0" }
+
+[dev_dependencies]
+soroban-sdk = { version = "=20.0.0", features = ["testutils"] }
+
+[features]
+testutils = ["soroban-sdk/testutils"]
+
+[profile.release]
+opt-level = "z"
+overflow-checks = true
+debug = 0
+strip = "symbols"
+debug-assertions = false
+panic = "abort"
+codegen-units = 1
+lto = true
+
+[profile.release-with-logs]
+inherits = "release"
+debug-assertions = true

test-cases/avoid-panic-error/avoid-panic-error-1/remediated-example/src/lib.rs

@@ -0,0 +1,69 @@
+#![no_std]
+use soroban_sdk::{contract, contracterror, contractimpl, symbol_short, Env, Symbol};
+
+const COUNTER: Symbol = symbol_short!("COUNTER");
+
+#[contract]
+pub struct AvoidPanicError;
+
+#[contracterror]
+#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+#[repr(u32)]
+pub enum Error {
+    OverflowError = 1,
+}
+
+#[contractimpl]
+impl AvoidPanicError {
+    pub fn add(env: Env, value: u32) -> Result<u32, Error> {
+        let storage = env.storage().instance();
+        let mut count: u32 = storage.get(&COUNTER).unwrap_or(0);
+        match count.checked_add(value) {
+            Some(value) => count = value,
+            None => return Err(Error::OverflowError),
+        }
+        storage.set(&COUNTER, &count);
+        storage.extend_ttl(100, 100);
+        Ok(count)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use soroban_sdk::Env;
+
+    use crate::{AvoidPanicError, AvoidPanicErrorClient, Error};
+
+    #[test]
+    fn add() {
+        // Given
+        let env = Env::default();
+        let contract_id = env.register_contract(None, AvoidPanicError);
+        let client = AvoidPanicErrorClient::new(&env, &contract_id);
+
+        // When
+        let first_increment = client.try_add(&1);
+        let second_increment = client.try_add(&2);
+        let third_increment = client.try_add(&3);
+
+        // Then
+        assert_eq!(first_increment, Ok(Ok(1)));
+        assert_eq!(second_increment, Ok(Ok(3)));
+        assert_eq!(third_increment, Ok(Ok(6)));
+    }
+
+    #[test]
+    fn overflow() {
+        // Given
+        let env = Env::default();
+        let contract_id = env.register_contract(None, AvoidPanicError);
+        let client = AvoidPanicErrorClient::new(&env, &contract_id);
+
+        // When
+        let _max_value = client.try_add(&u32::max_value());
+        let overflow = client.try_add(&1);
+
+        // Then
+        assert_eq!(overflow, Err(Ok(Error::OverflowError)));
+    }
+}

test-cases/avoid-panic-error/avoid-panic-error-1/vulnerable-example/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "avoid-panic-error-vulnerable-1"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+soroban-sdk = { version = "=20.0.0" }
+
+[dev_dependencies]
+soroban-sdk = { version = "=20.0.0", features = ["testutils"] }
+
+[features]
+testutils = ["soroban-sdk/testutils"]
+
+[profile.release]
+opt-level = "z"
+overflow-checks = true
+debug = 0
+strip = "symbols"
+debug-assertions = false
+panic = "abort"
+codegen-units = 1
+lto = true
+
+[profile.release-with-logs]
+inherits = "release"
+debug-assertions = true