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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
101 stars 23 forks source link

ITCM init #910

Open jordens opened 2 weeks ago

jordens commented 2 weeks 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 1 week 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 1 week 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 1 week 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.