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From: Michael Ellerman <michael@ellerman.id.au>
To: David Gibson <david@gibson.dropbear.id.au>,
	Serhii Popovych <spopovyc@redhat.com>
Cc: linux-kernel@vger.kernel.org, paulus@samba.org,
	linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org
Subject: Re: [PATCH 0/4] Fix use after free in HPT resizing code and related minor improvements
Date: Mon, 04 Dec 2017 23:22:47 +1100	[thread overview]
Message-ID: <87indmsmw8.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20171204061025.GQ2130@umbus.fritz.box>

David Gibson <david@gibson.dropbear.id.au> writes:

> On Wed, Nov 29, 2017 at 11:38:22AM -0500, Serhii Popovych wrote:
>> It is possible to trigger use after free during HPT resize
>> causing host kernel to crash. More details and analysis of
>> the problem can be found in change with corresponding subject
>> (KVM: PPC: Book3S HV: Fix use after free in case of multiple
>> resize requests).
>> 
>> We need some changes to prepare for the fix, especially
>> make ->error in HPT resize instance single point for
>> tracking allocation state, improve kvmppc_allocate_hpt()
>> and kvmppc_free_hpt() so they can be used more safely.
>> 
>> See individual commit description message to get more
>> information on changes presented.
>
> I spoke with Paul Mackerras about these patches on IRC today.  We want
> this as a fix, ASAP, in 4.15.  However, he's uncomfortable with
> pushing some of extra cleanups which aren't necessary for the bug fix
> this late for 4.15, and was having trouble following what was the core
> of the fix.  He was also nervous about the addition of more BUG_ON()s.

As was I.

> To avoid the round trip to Ukraine time and back, I've made revised
> versions of patches 1 & 3 which should apply standalone, replaced the
> BUG_ON()s with WARN_ON()s

Thanks.

cheers

WARNING: multiple messages have this Message-ID (diff)
From: Michael Ellerman <michael@ellerman.id.au>
To: David Gibson <david@gibson.dropbear.id.au>,
	Serhii Popovych <spopovyc@redhat.com>
Cc: linux-kernel@vger.kernel.org, paulus@samba.org,
	linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org
Subject: Re: [PATCH 0/4] Fix use after free in HPT resizing code and related minor improvements
Date: Mon, 04 Dec 2017 12:22:47 +0000	[thread overview]
Message-ID: <87indmsmw8.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20171204061025.GQ2130@umbus.fritz.box>

David Gibson <david@gibson.dropbear.id.au> writes:

> On Wed, Nov 29, 2017 at 11:38:22AM -0500, Serhii Popovych wrote:
>> It is possible to trigger use after free during HPT resize
>> causing host kernel to crash. More details and analysis of
>> the problem can be found in change with corresponding subject
>> (KVM: PPC: Book3S HV: Fix use after free in case of multiple
>> resize requests).
>> 
>> We need some changes to prepare for the fix, especially
>> make ->error in HPT resize instance single point for
>> tracking allocation state, improve kvmppc_allocate_hpt()
>> and kvmppc_free_hpt() so they can be used more safely.
>> 
>> See individual commit description message to get more
>> information on changes presented.
>
> I spoke with Paul Mackerras about these patches on IRC today.  We want
> this as a fix, ASAP, in 4.15.  However, he's uncomfortable with
> pushing some of extra cleanups which aren't necessary for the bug fix
> this late for 4.15, and was having trouble following what was the core
> of the fix.  He was also nervous about the addition of more BUG_ON()s.

As was I.

> To avoid the round trip to Ukraine time and back, I've made revised
> versions of patches 1 & 3 which should apply standalone, replaced the
> BUG_ON()s with WARN_ON()s

Thanks.

cheers

  reply	other threads:[~2017-12-04 12:22 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-29 16:38 [PATCH 0/4] Fix use after free in HPT resizing code and related minor improvements Serhii Popovych
2017-11-29 16:38 ` Serhii Popovych
2017-11-29 16:38 ` [PATCH 1/4] KVM: PPC: Book3S HV: Drop prepare_done from struct kvm_resize_hpt and cleanups Serhii Popovych
2017-11-29 16:38   ` Serhii Popovych
2017-11-30  3:40   ` David Gibson
2017-11-30  3:40     ` David Gibson
2017-11-29 16:38 ` [PATCH 2/4] KVM: PPC: Book3S HV: Improve kvmppc_allocate_hpt()/kvmppc_free_hpt() Serhii Popovych
2017-11-29 16:38   ` Serhii Popovych
2017-11-30  3:45   ` David Gibson
2017-11-30  3:45     ` David Gibson
2017-11-29 16:38 ` [PATCH 3/4] KVM: PPC: Book3S HV: Fix use after free in case of multiple resize requests Serhii Popovych
2017-11-29 16:38   ` Serhii Popovych
2017-11-30  3:51   ` David Gibson
2017-11-30  3:51     ` David Gibson
2017-11-29 16:38 ` [PATCH 4/4] KVM: PPC: Book3S HV: Remove redundant parameter from resize_hpt_release() Serhii Popovych
2017-11-29 16:38   ` Serhii Popovych
2017-11-30  3:53   ` David Gibson
2017-11-30  3:53     ` David Gibson
2017-11-30  3:54 ` [PATCH 0/4] Fix use after free in HPT resizing code and related minor improvements David Gibson
2017-11-30  3:54   ` David Gibson
2017-12-04  6:10 ` David Gibson
2017-12-04  6:10   ` David Gibson
2017-12-04 12:22   ` Michael Ellerman [this message]
2017-12-04 12:22     ` Michael Ellerman
2017-12-04 14:43   ` Serhii Popovych
2017-12-04 14:43     ` Serhii Popovych

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