Chen, Rong A <rong.a.chen@xxxxxxxxx> wrote: > On 11/22/2021 7:47 PM, Stephan Mueller wrote: > > Thanks for the notification. > > > > I think this is a false-positive discussed before. __latent_entropy is > > seemingly allowed for an entire linear buffer as seen in the declaration of > > the variable input_pool_data in driver/char/random.c which is an array of u32. > > > > The struct chacha20_state is a linear buffer of u32 words. > > > > struct chacha20_block { > > u32 constants[4]; > > union { > > u32 u[CHACHA_KEY_SIZE_WORDS]; > > u8 b[CHACHA_KEY_SIZE]; > > } key; > > u32 counter; > > u32 nonce[3]; > > }; > > > > Therefore it should be identical to the aforementioned example. No. It is a struct & there's no guarantee all compilers will lay it out as you expect. There might even be a gap in the layout since nonce[] has an odd number of elements. >> The __latent_entropy marker therefore seems to be appropriate for this structure. First, this is completely unnecessary since the input pool is marked for latent entropy & changes there will affect the chacha context. Also, if I'm reading the docs right, the __latent_entropy attribute on a data structure only gets it initialised somewhat randomly. If you want a continuous effect at runtime, then you need to make the code mix the latent_entropy global variable into the data structure.