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quartiq / stabilizer

Firmware and software for the Sinara Stabilizer module with high speed, low latency ADC/DAC data processing and powerful DSP algorithms in between
http://quartiq.de/stabilizer/
Apache License 2.0
111 stars 27 forks source link

ITCM init #910

Closed jordens closed 4 months ago

jordens commented 5 months ago

https://github.com/quartiq/stabilizer/blob/3ef00cbd92b9ee57b19026ba7abb3791e88be339/src/hardware/setup.rs#L183

That destination slice is uninitialized, thus insta-UB. Needs to be MaybeUninit.

ryan-summers commented 4 months ago

Not only that, but the pointer provenance of the sitcm pointer only permits us to technically write 4 bytes (because the static mut __sitcm: u32.

ryan-summers commented 4 months ago

Ref https://github.com/rust-embedded/wg/issues/771, it might be the case that pointer provenance is not actually an issue

jordens commented 4 months ago

Way back I had argued that this is like an FFI interface where one crates slices from addresses and lengths in a similar way without virtual machine knowing much about them. I.e. specifically the src slice must be fine to create like this. How else would one do it? And if the src slice is fine (initialized, doesn't break aliasing rules), so is the dst slice.

jordens commented 4 months ago

Closing as "not a problem".