Use the Scudo hardened allocator in example fuzzers

[langston-barrett]

The Scudo allocator (which is part of LLVM) "aims at providing additional mitigation against heap based vulnerabilities, while maintaining good performance". It is the default allocator in Android, and recently caught a near-miss memory corruption bug. There is an easy-to-use Rust binding, usage is as simple as:

#[global_allocator]
static SCUDO_ALLOCATOR: GlobalScudoAllocator = scudo::GlobalScudoAllocator;

LibAFL contains considerable amounts of unsafe code. Using this allocator in the example fuzzers might help catch additional memory corruption bugs during testing.

Just a suggestion, feel free to close if you don't like the idea!

[domenukk]

The performance of the fuzzer is probably more important than the memory safety of the fuzzer for us.
In the examples, we're using mimalloc with minimal security. This was the fastest option back when be benchmarked it.
That being said, setting the allocator has to be done by the downstream user and not inside a library. We could in theory have examples using Scudo and then try to find bugs in our own code, why not..
But in general I believe mimalloc is the way for our use case (unless there are faster ones in benchmarks)

[langston-barrett]

Oh sure! I was thinking just for testing / CI. For example, you could have a fuzzer that uses scudo in debug builds but mimalloc in release builds:

#[cfg(not(debug_assertions))]
#[global_allocator]
static ALLOCATOR: MiMalloc = mimalloc::MiMalloc;

#[cfg(debug_assertions)]
#[global_allocator]
static ALLOCATOR: GlobalScudoAllocator = scudo::GlobalScudoAllocator;

[domenukk]

Sure cannot hurt