Merge pull request #569 from CosmWasm/add-handle_vm_panic

Improve panic handling code and communication

Author: chipshort

libwasmvm/src/cache.rs

@@ -9,6 +9,7 @@ use serde::Serialize;
 use crate::api::GoApi;
 use crate::args::{CACHE_ARG, CHECKSUM_ARG, CONFIG_ARG, WASM_ARG};
 use crate::error::{handle_c_error_binary, handle_c_error_default, handle_c_error_ptr, Error};
+use crate::handle_vm_panic::handle_vm_panic;
 use crate::memory::{ByteSliceView, UnmanagedVector};
 use crate::querier::GoQuerier;
 use crate::storage::GoStorage;
@@ -31,7 +32,7 @@ pub extern "C" fn init_cache(
     error_msg: Option<&mut UnmanagedVector>,
 ) -> *mut cache_t {
     let r = catch_unwind(|| do_init_cache(config)).unwrap_or_else(|err| {
-        eprintln!("Panic in do_init_cache: {err:?}");
+        handle_vm_panic("do_init_cache", err);
         Err(Error::panic())
     });
     handle_c_error_ptr(r, error_msg) as *mut cache_t
@@ -56,7 +57,7 @@ pub extern "C" fn save_wasm(
     let r = match to_cache(cache) {
         Some(c) => catch_unwind(AssertUnwindSafe(move || do_save_wasm(c, wasm, unchecked)))
             .unwrap_or_else(|err| {
-                eprintln!("Panic in do_save_wasm: {err:?}");
+                handle_vm_panic("do_save_wasm", err);
                 Err(Error::panic())
             }),
         None => Err(Error::unset_arg(CACHE_ARG)),
@@ -88,7 +89,7 @@ pub extern "C" fn remove_wasm(
     let r = match to_cache(cache) {
         Some(c) => catch_unwind(AssertUnwindSafe(move || do_remove_wasm(c, checksum)))
             .unwrap_or_else(|err| {
-                eprintln!("Panic in do_remove_wasm: {err:?}");
+                handle_vm_panic("do_remove_wasm", err);
                 Err(Error::panic())
             }),
         None => Err(Error::unset_arg(CACHE_ARG)),
@@ -117,7 +118,7 @@ pub extern "C" fn load_wasm(
     let r = match to_cache(cache) {
         Some(c) => catch_unwind(AssertUnwindSafe(move || do_load_wasm(c, checksum)))
             .unwrap_or_else(|err| {
-                eprintln!("Panic in do_load_wasm: {err:?}");
+                handle_vm_panic("do_load_wasm", err);
                 Err(Error::panic())
             }),
         None => Err(Error::unset_arg(CACHE_ARG)),
@@ -147,7 +148,7 @@ pub extern "C" fn pin(
     let r = match to_cache(cache) {
         Some(c) => {
             catch_unwind(AssertUnwindSafe(move || do_pin(c, checksum))).unwrap_or_else(|err| {
-                eprintln!("Panic in do_pin: {err:?}");
+                handle_vm_panic("do_pin", err);
                 Err(Error::panic())
             })
         }
@@ -177,7 +178,7 @@ pub extern "C" fn unpin(
     let r = match to_cache(cache) {
         Some(c) => {
             catch_unwind(AssertUnwindSafe(move || do_unpin(c, checksum))).unwrap_or_else(|err| {
-                eprintln!("Panic in do_unpin: {err:?}");
+                handle_vm_panic("do_unpin", err);
                 Err(Error::panic())
             })
         }
@@ -285,7 +286,7 @@ pub extern "C" fn analyze_code(
     let r = match to_cache(cache) {
         Some(c) => catch_unwind(AssertUnwindSafe(move || do_analyze_code(c, checksum)))
             .unwrap_or_else(|err| {
-                eprintln!("Panic in do_analyze_code: {err:?}");
+                handle_vm_panic("do_analyze_code", err);
                 Err(Error::panic())
             }),
         None => Err(Error::unset_arg(CACHE_ARG)),
@@ -363,7 +364,7 @@ pub extern "C" fn get_metrics(
     let r = match to_cache(cache) {
         Some(c) => {
             catch_unwind(AssertUnwindSafe(move || do_get_metrics(c))).unwrap_or_else(|err| {
-                eprintln!("Panic in do_get_metrics: {err:?}");
+                handle_vm_panic("do_get_metrics", err);
                 Err(Error::panic())
             })
         }
@@ -418,7 +419,7 @@ pub extern "C" fn get_pinned_metrics(
     let r = match to_cache(cache) {
         Some(c) => {
             catch_unwind(AssertUnwindSafe(move || do_get_pinned_metrics(c))).unwrap_or_else(|err| {
-                eprintln!("Panic in do_get_pinned_metrics: {err:?}");
+                handle_vm_panic("do_get_pinned_metrics", err);
                 Err(Error::panic())
             })
         }

libwasmvm/src/calls.rs

@@ -19,6 +19,7 @@ use crate::args::{ARG1, ARG2, ARG3, CACHE_ARG, CHECKSUM_ARG, GAS_REPORT_ARG};
 use crate::cache::{cache_t, to_cache};
 use crate::db::Db;
 use crate::error::{handle_c_error_binary, Error};
+use crate::handle_vm_panic::handle_vm_panic;
 use crate::memory::{ByteSliceView, UnmanagedVector};
 use crate::querier::GoQuerier;
 use crate::storage::GoStorage;
@@ -528,7 +529,7 @@ fn call_2_args(
             )
         }))
         .unwrap_or_else(|err| {
-            eprintln!("Panic in do_call_2_args: {err:?}");
+            handle_vm_panic("do_call_2_args", err);
             Err(Error::panic())
         }),
         None => Err(Error::unset_arg(CACHE_ARG)),
@@ -622,7 +623,7 @@ fn call_3_args(
             )
         }))
         .unwrap_or_else(|err| {
-            eprintln!("Panic in do_call_3_args: {err:?}");
+            handle_vm_panic("do_call_3_args", err);
             Err(Error::panic())
         }),
         None => Err(Error::unset_arg(CACHE_ARG)),

libwasmvm/src/handle_vm_panic.rs

@@ -0,0 +1,34 @@
+use std::any::Any;
+
+/// A function to process cases in which the VM panics.
+///
+/// We want to provide as much debug information as possible
+/// as those cases are not expated to happen during healthy operations.
+pub fn handle_vm_panic(what: &str, err: Box<dyn Any + Send + 'static>) {
+    eprintln!("Panic in {what}:");
+    eprintln!("{err:?}"); // Does not show useful information, see https://users.rust-lang.org/t/return-value-from-catch-unwind-is-a-useless-any/89134/6
+    eprintln!(
+        "This indicates a panic in during the operations of libwasmvm/cosmwasm-vm.
+Such panics must not happen and are considered bugs. If you see this in any real-world or
+close-to-real-world usage of wasmvm, please consider filing a security report,
+no matter if it can be abused or not:
+(https://github.com/CosmWasm/advisories/blob/main/SECURITY.md#reporting-a-vulnerability).
+Thank you for your help keeping CosmWasm safe and secure 💚"
+    );
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use std::panic::catch_unwind;
+
+    #[test]
+    fn handle_vm_panic_works() {
+        fn nice_try() {
+            panic!("oh no!");
+        }
+        let err = catch_unwind(nice_try).unwrap_err();
+        handle_vm_panic("nice_try", err);
+    }
+}

libwasmvm/src/lib.rs

@@ -9,6 +9,7 @@ mod db;
 mod error;
 mod gas_meter;
 mod gas_report;
+mod handle_vm_panic;
 mod iterator;
 mod memory;
 mod querier;