Merge #7116

7116: Fix deep syntax tree bug generated by proc-macro r=jonas-schievink a=edwin0cheng

This PR fixed a bug from `semver-parser` and `pest_derive` crates which generate a very deep syntax tree such that serde reject to de-serialize. To fix this bug, we disabled recursion limit in `serde` (by calling [`Deserializer::disable_recursion_limit`](https://docs.rs/serde_json/1.0.61/serde_json/struct.Deserializer.html#method.disable_recursion_limit))

I have a feeling that we still need some way to protect against bad proc-macro generating huge syntax node, but I have no  idea right now.

r? @jonas-schievink 

Fixes #7103 

Co-authored-by: Edwin Cheng <[email protected]>

2 files changed, 11 insertions, 4 deletions

diff --git a/crates/proc_macro_api/src/msg.rs b/crates/proc_macro_api/src/msg.rs
index f84ebdbc5..4cd572101 100644
--- a/crates/proc_macro_api/src/msg.rs
+++ b/crates/proc_macro_api/src/msg.rs
@@ -58,7 +58,13 @@ pub trait Message: Serialize + DeserializeOwned {
     fn read(inp: &mut impl BufRead) -> io::Result<Option<Self>> {
         Ok(match read_json(inp)? {
             None => None,
-            Some(text) => Some(serde_json::from_str(&text)?),
+            Some(text) => {
+                let mut deserializer = serde_json::Deserializer::from_str(&text);
+                // Note that some proc-macro generate very deep syntax tree
+                // We have to disable the current limit of serde here
+                deserializer.disable_recursion_limit();
+                Some(Self::deserialize(&mut deserializer)?)
+            }
         })
     }
     fn write(self, out: &mut impl Write) -> io::Result<()> {
diff --git a/crates/proc_macro_api/src/process.rs b/crates/proc_macro_api/src/process.rs
index d68723ada..6d6ab8888 100644
--- a/crates/proc_macro_api/src/process.rs
+++ b/crates/proc_macro_api/src/process.rs
@@ -92,10 +92,11 @@ fn client_loop(task_rx: Receiver<Task>, mut process: Process) {
     for Task { req, result_tx } in task_rx {
         match send_request(&mut stdin, &mut stdout, req) {
             Ok(res) => result_tx.send(res).unwrap(),
-            Err(_err) => {
+            Err(err) => {
                 log::error!(
-                    "proc macro server crashed, server process state: {:?}",
-                    process.child.try_wait()
+                    "proc macro server crashed, server process state: {:?}, server request error: {:?}",
+                    process.child.try_wait(),
+                    err
                 );
                 let res = Response::Error(ResponseError {
                     code: ErrorCode::ServerErrorEnd,