Re: [PATCH RESEND] KEYS: fix parsing invalid pkey info string

[Dmitry Vyukov]

On Mon, Dec 17, 2018 at 7:43 PM Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Mon, Dec 17, 2018 at 10:13 AM Eric Biggers <ebiggers@xxxxxxxxxx> wrote:
> >
> > Hi Linus, please consider applying this patch.  It's been ignored by the
> > keyrings maintainer for a month and a half with multiple reminders.  It
> > fixes an easily reachable stack corruption in the new keyctl operations
> > that were added in v4.20.  It was immediately reached by syzbot even
> > without any definitions for the new keyctls yet.
>
> The getoptions() code in security/keys/trusted.c has exactly the same
> buggy pattern, and seems to actually be the source of that idiocy.
>
> Mind fixing that one too and getting rid of this incorrect code entirely?
>
> Also, maybe the right fix is to do the "check for duplicate tokens"
> only *after* all the other validation (ie after the switch())?
>
> Or maybe just remove it entirely, since it's clearly entirely
> incorrect from the very start.
>
> Finally, the code was actually originally introduced in commit
> 5208cc83423d ("keys, trusted: fix: *do not* allow duplicate key
> options"), this second place you found is just pattern matching from
> that original garbage, that was acked and "reviewed" by several
> people.

... also acked by 0 tests added by that commit.

> The fix should have that clarification. Commit 00d60fd3b932
> wasn't the _origin_ of this bug, even if it made a copy of it.
>
> Looking around, nobody else has picked up that incorrect pattern.
>
>                    Linus
>
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