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Date: Thu, 14 May 2020 05:00:18 -0700 From: Matthew Wilcox <willy@...radead.org> To: Balbir Singh <bsingharora@...il.com> Cc: Waiman Long <longman@...hat.com>, Andrew Morton <akpm@...ux-foundation.org>, David Howells <dhowells@...hat.com>, Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>, James Morris <jmorris@...ei.org>, "Serge E. Hallyn" <serge@...lyn.com>, linux-mm@...ck.org, keyrings@...r.kernel.org, linux-kernel@...r.kernel.org, Linus Torvalds <torvalds@...ux-foundation.org>, Joe Perches <joe@...ches.com>, David Rientjes <rientjes@...gle.com> Subject: Re: [PATCH v3] mm: Add kvfree_sensitive() for freeing sensitive data objects 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.
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