From: Quentin Perret <qperret@google.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
James Morse <james.morse@arm.com>, Will Deacon <will@kernel.org>,
kernel-team@android.com
Subject: Re: [PATCH] KVM: arm64: Prevent kmemleak from accessing pKVM memory
Date: Fri, 17 Jun 2022 08:45:48 +0000 [thread overview]
Message-ID: <Yqw/PI6jF5HZTvxB@google.com> (raw)
In-Reply-To: <Yqw9dou3qgpAKQkZ@kernel.org>
On Friday 17 Jun 2022 at 11:38:14 (+0300), Mike Rapoport wrote:
> On Fri, Jun 17, 2022 at 09:21:31AM +0100, Marc Zyngier wrote:
> > On Thu, 16 Jun 2022 16:11:34 +0000, Quentin Perret wrote:
> > > Commit a7259df76702 ("memblock: make memblock_find_in_range method
> > > private") changed the API using which memory is reserved for the pKVM
> > > hypervisor. However, it seems that memblock_phys_alloc() differs
> > > from the original API in terms of kmemleak semantics -- the old one
> > > excluded the reserved regions from kmemleak scans when the new one
> > > doesn't seem to. Unfortunately, when protected KVM is enabled, all
> > > kernel accesses to pKVM-private memory result in a fatal exception,
> > > which can now happen because of kmemleak scans:
> > >
> > > [...]
> >
> > Applied to fixes, thanks!
> >
> > [1/1] KVM: arm64: Prevent kmemleak from accessing pKVM memory
> > commit: 9e5afa8a537f742bccc2cd91bc0bef4b6483ee98
>
> I'd really like to update the changelog to this:
>
> Commit a7259df76702 ("memblock: make memblock_find_in_range method
> private") changed the API using which memory is reserved for the pKVM
> hypervisor. However, memblock_phys_alloc() differs from the original API in
> terms of kmemleak semantics -- the old one didn't report the reserved
> regions to kmemleak while the new one does. Unfortunately, when protected
> KVM is enabled, all kernel accesses to pKVM-private memory result in a
> fatal exception, which can now happen because of kmemleak scans:
>
> $ echo scan > /sys/kernel/debug/kmemleak
> [ 34.991354] kvm [304]: nVHE hyp BUG at: [<ffff800008fa3750>] __kvm_nvhe_handle_host_mem_abort+0x270/0x290!
> ...
>
> Fix this by explicitly excluding the hypervisor's memory pool from
> kmemleak like we already do for the hyp BSS.
Looks good to me, thanks.
Quentin
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next prev parent reply other threads:[~2022-06-17 8:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-16 16:11 [PATCH] KVM: arm64: Prevent kmemleak from accessing pKVM memory Quentin Perret
2022-06-16 17:51 ` Catalin Marinas
2022-06-17 8:19 ` Mike Rapoport
2022-06-17 8:21 ` Marc Zyngier
2022-06-17 8:38 ` Mike Rapoport
2022-06-17 8:45 ` Quentin Perret [this message]
2022-06-17 8:50 ` Marc Zyngier
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