From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Alex Dewar <alex.dewar90@gmail.com>
Cc: David Howells <dhowells@redhat.com>,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
keyrings@vger.kernel.org, linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] security: keys: Use kvfree_sensitive in a few places
Date: Fri, 11 Sep 2020 08:04:24 -0700 [thread overview]
Message-ID: <1599836664.4041.21.camel@HansenPartnership.com> (raw)
In-Reply-To: <20200911114400.82207-1-alex.dewar90@gmail.com>
On Fri, 2020-09-11 at 12:44 +0100, Alex Dewar wrote:
> In big_key.c, there are a few places where memzero_explicit + kvfree
> is used. It is better to use kvfree_sensitive instead, which is more
> readable and also prevents the compiler from eliding the call to
> memzero_explicit. Fix this.
That last bit is untrue: the compiler can't elide memzero_explicit ...
that's why it has the explicit suffix.
The original problem was a lot of people do memset(.., 0, ..); kfree()
which the compiler can elide if it understands the memory is going out
of scope. Or the even more problematic memset(..., 0, ...) on a stack
variable before it goes out of scope.
We can argue about readability but there's no secret leak here.
James
next prev parent reply other threads:[~2020-09-11 16:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-11 11:44 Alex Dewar
2020-09-11 15:04 ` James Bottomley [this message]
2020-09-11 16:05 ` Denis Efremov
2020-09-11 16:09 ` Alex Dewar
2020-09-14 18:05 ` Jarkko Sakkinen
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