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From: David Howells <dhowells@redhat.com>
In-Reply-To: <20170403175929.GB72831@gmail.com>
References: <20170403175929.GB72831@gmail.com> <20170401213428.17097-1-ebiggers3@gmail.com> <3451.1491234402@warthog.procyon.org.uk>
To: Eric Biggers <ebiggers3@gmail.com>
Cc: dhowells@redhat.com, keyrings@vger.kernel.org,
        linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org,
        Eric Biggers <ebiggers@google.com>, stable@vger.kernel.org
Subject: Re: [PATCH] KEYS: fix dereferencing NULL payload with nonzero length
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Date: Mon, 03 Apr 2017 20:20:44 +0100
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Eric Biggers <ebiggers3@gmail.com> wrote:

> > > -	if (_payload) {
> > > +	if (plen) {
> > 
> > "if (_payload && plen)" would be better.
> > 
> > David
> 
> No, that doesn't solve the problem.  The problem is that userspace can pass
> in a NULL payload with nonzero length, causing the kernel to dereference a
> NULL pointer for some key types.  For example:

Okay, in that case, I think there should be an else-statement that clears plen
if !_payload.

David