Messages in this thread | | | Date | Mon, 7 Feb 2022 21:09:28 +0200 | Subject | Re: [PATCH v9 42/43] virt: sevguest: Add support to derive key | From | Dov Murik <> |
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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
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