linux-kernel - Re: [RFC v1] copy_{to,from}_user(): only inline when !__CHECKER_

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Message-ID: <20181209210220.GB2217@ZenIV.linux.org.uk>
Date:   Sun, 9 Dec 2018 21:02:21 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Tycho Andersen <tycho@...ho.ws>
Cc:     linux-sparse@...r.kernel.org, kernel-hardening@...ts.openwall.com,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC v1] copy_{to,from}_user(): only inline when !__CHECKER__

On Sun, Dec 09, 2018 at 01:44:49PM -0700, Tycho Andersen wrote:
> While working on some additional copy_to_user() checks for sparse, I
> noticed that sparse's current copy_to_user() checks are not triggered. This
> is because copy_to_user() is declared as __always_inline, and sparse
> specifically looks for a call instruction to copy_to_user() when it tries
> to apply the checks.
> 
> A quick fix is to explicitly not inline when __CHECKER__ is defined, so
> that sparse will be able to analyze all the copy_{to,from}_user calls.
> There may be some refactoring in sparse that we can do to fix this,
> although it's not immediately obvious to me how, hence the RFC-ness of this
> patch.

Which sparse checks do not trigger?  Explain, please - as it is, I had been
unable to guess what could "specifically looks for a call instruction" refer
to.