On 07/02/2022 18:23, Brijesh Singh wrote: > > > On 2/7/22 2:52 AM, Borislav Petkov wrote: >> Those are allocated on stack, why are you clearing them? > > Yep, no need to explicitly clear it. I'll take it out in next rev. > Wait, this is key material generated by PSP and passed to userspace. Why leave copies of it floating around kernel memory? I thought that's the whole reason for these memzero_explicit() calls (maybe add a comment?). As an example, in arch/x86/crypto/aesni-intel_glue.c there are two calls to memzero_explicit(), both on stack variables; the only reason for these calls (as I understand it) is to avoid some future possible leak of this sensitive data (keys, cipher context, etc.). I'm sure there are other examples in the kernel code. -Dov
