Messages in this thread | | | Subject | Re: [PATCH v3] mm: Add kvfree_sensitive() for freeing sensitive data objects | From | Balbir Singh <> | Date | Sun, 17 May 2020 10:27:39 +1000 |
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On 14/5/20 10:00 pm, Matthew Wilcox wrote: > On Thu, May 14, 2020 at 09:00:40PM +1000, Balbir Singh wrote: >> I wonder if the right thing to do is also to disable pre-emption, just so that the thread does not linger on with sensitive data. >> >> void kvfree_sensitive(const void *addr, size_t len) >> { >> preempt_disable(); >> if (likely(!ZERO_OR_NULL_PTR(addr))) { >> memzero_explicit((void *)addr, len); >> kvfree(addr); >> } >> preempt_enable(); >> } >> EXPORT_SYMBOL(kvfree_sensitive); > > If it's _that_ sensitive then the caller should have disabled preemption. > Because preemption could otherwise have occurred immediately before > kvfree_sensitive() was called. >
May be, but the callers of the API have to be explictly aware of the contract. I don't disagree with you on what you've said, but I was referring to the intent of freeing sensitive data vs the turn around time for doing so.
Balbir Singh.
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