Messages in this thread | | | Date | Tue, 6 Jan 2015 20:42:26 +0100 | From | Giel van Schijndel <> | Subject | Re: [PATCH] Use memzero_explicit to clear local buffers |
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On Mon, Jan 05, 2015 at 10:36:37 +1100, Herbert Xu wrote: > On Sun, Jan 04, 2015 at 11:49:09PM +0100, Giel van Schijndel wrote: >> >>> sctx does not point to stack memory so this is bogus. >>> >>> Only stack memory cleared just before it goes out of scope needs >>> memzero_explicit. >> >> Is that because the compiler can't safely optimize memset(0) away for a >> variable with greater-than-local scope? > > Exactly. memzero_explicit is not a marker for sensitive data. > Its only purpose is to prevent the compiler from optimising away > zeroing that occurs at the end of a scope.
Question: are you sure the compiler won't optimize the call to memset(0) way if it's immediately followed by kfree()?
Because one of my changes concerns that situation.
Another actually does change a stack-allocated buffer, I'll split that one off right away.
-- Met vriendelijke groet, With kind regards, Giel van Schijndel -- "When all you have is a hammer, everything starts to look like a nail." -- Abraham Maslow [unhandled content-type:application/pgp-signature] | |