New error in libfl 0.9.0

[cokeBeer]

Describe the bug
Atfer I upgraded my libafl version from 0.8.x ( rev = "7ed1ac9" ) to 0.9.0, my code suddenly encountered some runtime errors.

To Reproduce
Steps to reproduce the behavior:

1. load corpus from disk like

    state
        .load_initial_inputs_forced(&mut fuzzer, &mut executor, &mut mgr, corpus_dirs)
        .unwrap_or_else(|_| panic!("Failed to load initial corpus at {:?}",&corpus_dirs));
        println!("We imported {} inputs from disk.", state.corpus().count());

2. run fuzz like

while state.solutions().is_empty() {
            fuzzer.fuzz_one(&mut stages, &mut executor, &mut state, &mut mgr)?;
        }

Expected behavior
get a runtime error

Loading file "./corpus\\case1" ...
abcd
[Testcase #0] run time: 0h-0m-0s, clients: 1, corpus: 1, objectives: 0, executions: 1, exec/sec: 0.000
[LOG Debug]: Loaded 1 initial testcases.
We imported 1 inputs from disk.
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', C:\Users\Administrator\.cargo\registry\src\github.aaakk.us.kg-1ecc6299db9ec823\libafl-0.9.0\src\stages\mutational.rs:76:34github.com-1ecc6299db9ec823\libafl-0.9.0\src\stages\mutational.rs:76:34
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Crashed with STATUS_ILLEGAL_INSTRUCTION
Double crash

We crashed at addr 0x7ff792fcb9e8, but are not in the target... Bug in the fuzzer? Exiting.
Type QUIT to restart the child

which is from

impl<I, S> MutatedTransform<I, S> for I
where
    I: Input + Clone,
{
    type Post = ();

    #[inline]
    fn try_transform_from(
        base: &Testcase<I>,
        _state: &S,
        _corpus_idx: CorpusId,
    ) -> Result<Self, Error> {
        Ok(base.input().as_ref().unwrap().clone()) // here 
    }

    #[inline]
    fn try_transform_into(self, _state: &S) -> Result<(I, Self::Post), Error> {
        Ok((self, ()))
    }
}

Screen output/Screenshots
If applicable, add copy-paste of the screen output or screenshot that shows the issue. Please ensure the output is in English and not in Chinese, Russian, German, etc.

Additional context
My code works well in 0.8.x and I update some new apis in 0.9.0 to fix errors reported by static analyse.
So how can I fix this runtime error?

[domenukk]

What input and corpus do you use?
Cc @andreafioraldi

[cokeBeer]

testcase: abcd
input: BytesInput
corpus: OnDiskCorpus

[f0rki]

I encountered the same issue and fixed it like this:

diff --git a/libafl/src/stages/mutational.rs b/libafl/src/stages/mutational.rs
index d5120313..e68c170d 100644
--- a/libafl/src/stages/mutational.rs
+++ b/libafl/src/stages/mutational.rs
@@ -73,7 +73,11 @@ where
         _state: &S,
         _corpus_idx: CorpusId,
     ) -> Result<Self, Error> {
-        Ok(base.input().as_ref().unwrap().clone())
+        if let Some(i) = base.input().as_ref() {
+            Ok(i.clone())
+        } else {
+            Ok(base.clone().load_input()?.clone())
+        }
     }

     #[inline]
--

[addisoncrump]

This change is correct @f0rki, would you be willing to submit a PR?

[addisoncrump]

Fixed by #1077