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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 17 Dec 2018 12:02:01 -0800
Message-ID: <CAHk-=wjPhKNKRq24wXL3wvqUgfyriDjYNXUPCumbH=64ZMXrSw@mail.gmail.com>
Subject: Re: [PATCH RESEND] KEYS: fix parsing invalid pkey info string
To:     James Bottomley <James.Bottomley@hansenpartnership.com>
Cc:     ebiggers@kernel.org, James Morris James Morris <jmorris@namei.org>,
        Mimi Zohar <zohar@linux.vnet.ibm.com>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Peter Huewe <peterhuewe@gmx.de>,
        David Howells <dhowells@redhat.com>, keyrings@vger.kernel.org,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        syzkaller-bugs@googlegroups.com
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On Mon, Dec 17, 2018 at 11:51 AM James Bottomley
<James.Bottomley@hansenpartnership.com> wrote:
>
> If this is to replace Eric's patch, didn't you want to set token_mask
> to (1<<Opt_err)?

No, let's not add any extra code that is trying to be subtle. Subtle
interactions was where the bug came from.

The code already checks the actual Opt_xyz for errors in a switch
statement. The token_mask should be _purely_ about duplicate options
(or conflicting ones).

Talking about the conflicting ones: Opt_hash checks that
Opt_policydigest isn't set. But Opt_policydigest doesn't check that
Opt_hash isn't set, so you can mix the two if you just do it in the
right order.

But that's a separate bug, and doesn't seem to be a huge deal.

But it *is* an example of how bogus all of this stuff is. Clearly
people weren't really paying attention when writing any of this code.

                        Linus