Merge #1192

1192: Add mbe expand limit and poision macro set r=maklad a=edwin0cheng

As discussed in Zulip, this PR add a token expansion limit in `parse_macro` and a "poison" macro set in `CrateDefMap` to prevent stack over flow and limit a mbe macro size.

Note:
Right now it only handle a poison macro in a single crate, such that if other crate try to call that macro, the whole process will do again until it became poisoned in that crate.


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

1 files changed, 7 insertions, 0 deletions

diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index e771a311c..c7849c995 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -94,6 +94,13 @@ fn parse_macro(
 
     let macro_rules = db.macro_def(loc.def).ok_or("Fail to find macro definition")?;
     let tt = macro_rules.expand(&macro_arg).map_err(|err| format!("{:?}", err))?;
+
+    // Set a hard limit for the expanded tt
+    let count = tt.count();
+    if count > 65536 {
+        return Err(format!("Total tokens count exceed limit : count = {}", count));
+    }
+
     Ok(mbe::token_tree_to_ast_item_list(&tt))
 }