From: Michael Ellerman <mpe@ellerman.id.au>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>
Cc: Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
linuxppc-dev@lists.ozlabs.org,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
linux-s390 <linux-s390@vger.kernel.org>,
Nicholas Piggin <npiggin@gmail.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Paul Mackerras <paulus@ozlabs.org>
Subject: Re: Linux 5.1-rc5
Date: Wed, 17 Apr 2019 13:38:33 +1000 [thread overview]
Message-ID: <87sguhti6e.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <CAHk-=wj7jgMOVFW0tiU-X+zhg6+Rn7mEBTej+f26rV3zXezOSA@mail.gmail.com>
[ Cc += Nick & Aneesh & Paul ]
Linus Torvalds <torvalds@linux-foundation.org> writes:
> On Sun, Apr 14, 2019 at 10:19 PM Christoph Hellwig <hch@infradead.org> wrote:
>>
>> Can we please have the page refcount overflow fixes out on the list
>> for review, even if it is after the fact?
>
> They were actually on a list for review long before the fact, but it
> was the security mailing list. The issue actually got discussed back
> in January along with early versions of the patches, but then we
> dropped the ball because it just wasn't on anybody's radar and it got
> resurrected late March. Willy wrote a rather bigger patch-series, and
> review of that is what then resulted in those commits. So they may
> look recent, but that's just because the original patches got
> seriously edited down and rewritten.
>
> That said, powerpc and s390 should at least look at maybe adding a
> check for the page ref in their gup paths too. Powerpc has the special
> gup_hugepte() case
Which uses page_cache_add_speculative(), which handles the case of the
refcount being zero but not overflow. So that looks like it needs
fixing.
We also have follow_huge_pd() that should use try_get_page().
And we have a few uses of bare get_page() in KVM code which might be
subject to the same attack.
cheers
next prev parent reply other threads:[~2019-04-17 3:38 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-14 22:40 Linux 5.1-rc5 Linus Torvalds
2019-04-15 5:19 ` Christoph Hellwig
2019-04-15 16:17 ` Linus Torvalds
2019-04-16 9:09 ` Martin Schwidefsky
2019-04-16 12:06 ` Martin Schwidefsky
2019-04-16 16:16 ` Linus Torvalds
2019-04-16 16:49 ` Linus Torvalds
2019-04-17 7:46 ` Martin Schwidefsky
2019-04-17 8:02 ` Martin Schwidefsky
2019-04-17 16:57 ` Linus Torvalds
2019-04-18 8:02 ` Martin Schwidefsky
2019-04-18 15:49 ` Linus Torvalds
2019-04-18 18:41 ` Martin Schwidefsky
2019-04-19 13:33 ` Martin Schwidefsky
2019-04-19 17:27 ` Linus Torvalds
2019-04-23 15:38 ` Martin Schwidefsky
2019-04-23 16:06 ` Linus Torvalds
2019-04-17 3:38 ` Michael Ellerman [this message]
2019-04-17 4:13 ` Linus Torvalds
2019-05-02 12:21 ` Greg KH
2019-05-02 14:17 ` Martin Schwidefsky
2019-05-02 14:31 ` Greg KH
2019-05-02 15:10 ` Martin Schwidefsky
2019-05-20 11:09 ` Greg KH
2019-05-03 13:31 ` Michael Ellerman
2019-05-02 23:15 ` Christoph Hellwig
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