Re: [PATCH v2 4/4] rust: devres: implement register_release()

[Benno Lossin]

On Mon Jun 23, 2025 at 2:51 PM CEST, Danilo Krummrich wrote:
> On Mon, Jun 23, 2025 at 12:01:14PM +0000, Alice Ryhl wrote:
>> On Sun, Jun 22, 2025 at 06:40:41PM +0200, Danilo Krummrich wrote:
>> > +pub fn register_release<P>(dev: &Device<Bound>, data: P) -> Result
>> > +where
>> > +    P: ForeignOwnable,
>> > +    for<'a> P::Borrowed<'a>: Release,
>> 
>> I think we need where P: ForeignOwnable + 'static too.
>> 
>> otherwise I can pass something with a reference that expires before the
>> device is unbound and access it in the devm callback as a UAF.
>
> I can't really come up with an example for such a case, mind providing one? :)

    {
        let local = MyLocalData { /* ... */ };
        let data = Arc::new(Data { r: &local });
        devres::register_release(dev, data)?;
    }
    // devres still holds onto `data`, but that points at `MyLocalData`
    // which is on the stack and freed here...

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Cheers,
Benno