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feat(runtime-c-api) Check buffer size before creating the slice, and fix wasmer_last_error_message returned value #432

Merged
merged 6 commits into from
May 13, 2019
16 changes: 8 additions & 8 deletions lib/runtime-c-api/src/error.rs
Original file line number Diff line number Diff line change
Expand Up @@ -61,20 +61,20 @@ pub unsafe extern "C" fn wasmer_last_error_message(buffer: *mut c_char, length:
return -1;
}

let last_error = match take_last_error() {
Some(err) => err,
let error_message = match take_last_error() {
Some(err) => err.to_string(),
None => return 0,
};

let error_message = last_error.to_string();
let length = length as usize;

let buffer = slice::from_raw_parts_mut(buffer as *mut u8, length as usize);

if error_message.len() >= buffer.len() {
// buffer to small for err message
if error_message.len() >= length {
// buffer to small to hold the error message
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return -1;
}

let buffer = slice::from_raw_parts_mut(buffer as *mut u8, length);

ptr::copy_nonoverlapping(
error_message.as_ptr(),
buffer.as_mut_ptr(),
Expand All @@ -85,7 +85,7 @@ pub unsafe extern "C" fn wasmer_last_error_message(buffer: *mut c_char, length:
// accidentally read into garbage.
buffer[error_message.len()] = 0;

error_message.len() as c_int
error_message.len() as c_int + 1
}

#[derive(Debug)]
Expand Down