Merge #1006

1006: fix 1005 panic sub overflow r=MarkMcCaskey a=pventuzelo # Description Fix issue #1005 # Review - [x] Add a short description of the the change to the CHANGELOG.md file Co-authored-by: Patrick Ventuzelo <[email protected]> Co-authored-by: Patrick Ventuzelo <[email protected]>
wasmerio · Nov 27, 2019 · f6f8780 · f6f8780
2 parents 53f0a9c + bb16547
commit f6f8780
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## **[Unreleased]**
 
+- [#1006](https://github.com/wasmerio/wasmer/pull/1006) Fix minor panic issue when `wasmer::compile_with` called with llvm backend
 - [#1009](https://github.com/wasmerio/wasmer/pull/1009) Enable LLVM verifier for all tests, add new llvm-backend-tests crate.
 
 ## 0.11.0 - 2019-11-22

diff --git a/lib/llvm-backend/src/state.rs b/lib/llvm-backend/src/state.rs
@@ -336,12 +336,12 @@ impl State {
         &self,
         n: usize,
     ) -> Result<&[(BasicValueEnum, ExtraInfo)], BinaryReaderError> {
-        self.stack
-            .get(self.stack.len() - n..)
-            .ok_or(BinaryReaderError {
-                message: "invalid value stack",
-                offset: -1isize as usize,
-            })
+        let new_len = self.stack.len().checked_sub(n).ok_or(BinaryReaderError {
+            message: "invalid value stack",
+            offset: -1isize as usize,
+        })?;
+
+        Ok(&self.stack[new_len..])
     }
 
     pub fn popn_save_extra(