From: Marc Zyngier <marc.zyngier@arm.com>
To: Andre Przywara <andre.przywara@arm.com>,
Christoffer Dall <christoffer.dall@linaro.org>
Cc: kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
Cosmin Gorgovan <cosmin@linux-geek.org>,
stable@vger.kernel.org
Subject: Re: [PATCH] KVM: arm/arm64: fix reference to uninitialised VGIC
Date: Wed, 3 Feb 2016 17:33:54 +0000 [thread overview]
Message-ID: <56B23A02.7070804@arm.com> (raw)
In-Reply-To: <1454518611-15694-1-git-send-email-andre.przywara@arm.com>
On 03/02/16 16:56, Andre Przywara wrote:
> Commit 4b4b4512da2a ("arm/arm64: KVM: Rework the arch timer to use
> level-triggered semantics") brought the virtual architected timer
> closer to the VGIC. There is one occasion were we don't properly
> check for the VGIC actually having been initialized before, but
> instead go on to check the active state of some IRQ number.
> If userland hasn't instantiated a virtual GIC, we end up with a
> kernel NULL pointer dereference:
> =========
> Unable to handle kernel NULL pointer dereference at virtual address 00000000
> pgd = ffffffc9745c5000
> [00000000] *pgd=00000009f631e003, *pud=00000009f631e003, *pmd=0000000000000000
> Internal error: Oops: 96000006 [#2] PREEMPT SMP
> Modules linked in:
> CPU: 0 PID: 2144 Comm: kvm_simplest-ar Tainted: G D 4.5.0-rc2+ #1300
> Hardware name: ARM Juno development board (r1) (DT)
> task: ffffffc976da8000 ti: ffffffc976e28000 task.ti: ffffffc976e28000
> PC is at vgic_bitmap_get_irq_val+0x78/0x90
> LR is at kvm_vgic_map_is_active+0xac/0xc8
> pc : [<ffffffc0000b7e28>] lr : [<ffffffc0000b972c>] pstate: 20000145
> ....
> =========
>
> Fix this by bailing out early of kvm_timer_flush_hwstate() if we don't
> have a VGIC at all.
>
> Reported-by: Cosmin Gorgovan <cosmin@linux-geek.org>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> Cc: <stable@vger.kernel.org> # 4.4.x
Nice catch, thanks.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2016-02-03 17:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-03 16:56 [PATCH] KVM: arm/arm64: fix reference to uninitialised VGIC Andre Przywara
2016-02-03 17:33 ` Marc Zyngier [this message]
2016-02-04 7:36 ` Pavel Fedin
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