From: Janosch Frank <frankja@linux.ibm.com>
To: Claudio Imbrenda <imbrenda@linux.ibm.com>, kvm@vger.kernel.org
Cc: cohuck@redhat.com, borntraeger@de.ibm.com, thuth@redhat.com,
pasic@linux.ibm.com, david@redhat.com,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
Ulrich.Weigand@de.ibm.com
Subject: Re: [PATCH v5 02/14] KVM: s390: pv: avoid double free of sida page
Date: Tue, 5 Oct 2021 15:11:47 +0200 [thread overview]
Message-ID: <440d852f-ae4e-7466-ecb8-c60890a6d849@linux.ibm.com> (raw)
In-Reply-To: <20210920132502.36111-3-imbrenda@linux.ibm.com>
On 9/20/21 15:24, Claudio Imbrenda wrote:
> If kvm_s390_pv_destroy_cpu is called more than once, we risk calling
> free_page on a random page, since the sidad field is aliased with the
> gbea, which is not guaranteed to be zero.
>
> This can happen, for example, if userspace calls the KVM_PV_DISABLE
> IOCTL, and it fails, and then userspace calls the same IOCTL again.
> This scenario is only possible if KVM has some serious bug or if the
> hardware is broken.
>
> The solution is to simply return successfully immediately if the vCPU
> was already non secure.
>
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> Fixes: 19e1227768863a1469797c13ef8fea1af7beac2c ("KVM: S390: protvirt: Introduce instruction data area bounce buffer")
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
> ---
> arch/s390/kvm/pv.c | 19 +++++++++----------
> 1 file changed, 9 insertions(+), 10 deletions(-)
>
> diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
> index c8841f476e91..0a854115100b 100644
> --- a/arch/s390/kvm/pv.c
> +++ b/arch/s390/kvm/pv.c
> @@ -16,18 +16,17 @@
>
> int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc)
> {
> - int cc = 0;
> + int cc;
>
> - if (kvm_s390_pv_cpu_get_handle(vcpu)) {
> - cc = uv_cmd_nodata(kvm_s390_pv_cpu_get_handle(vcpu),
> - UVC_CMD_DESTROY_SEC_CPU, rc, rrc);
> + if (!kvm_s390_pv_cpu_get_handle(vcpu))
> + return 0;
> +
> + cc = uv_cmd_nodata(kvm_s390_pv_cpu_get_handle(vcpu), UVC_CMD_DESTROY_SEC_CPU, rc, rrc);
> +
> + KVM_UV_EVENT(vcpu->kvm, 3, "PROTVIRT DESTROY VCPU %d: rc %x rrc %x",
> + vcpu->vcpu_id, *rc, *rrc);
> + WARN_ONCE(cc, "protvirt destroy cpu failed rc %x rrc %x", *rc, *rrc);
>
> - KVM_UV_EVENT(vcpu->kvm, 3,
> - "PROTVIRT DESTROY VCPU %d: rc %x rrc %x",
> - vcpu->vcpu_id, *rc, *rrc);
> - WARN_ONCE(cc, "protvirt destroy cpu failed rc %x rrc %x",
> - *rc, *rrc);
> - }
> /* Intended memory leak for something that should never happen. */
> if (!cc)
> free_pages(vcpu->arch.pv.stor_base,
>
next prev parent reply other threads:[~2021-10-05 13:12 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 13:24 [PATCH v5 00/14] KVM: s390: pv: implement lazy destroy for reboot Claudio Imbrenda
2021-09-20 13:24 ` [PATCH v5 01/14] KVM: s390: pv: add macros for UVC CC values Claudio Imbrenda
2021-10-05 13:08 ` Janosch Frank
2021-09-20 13:24 ` [PATCH v5 02/14] KVM: s390: pv: avoid double free of sida page Claudio Imbrenda
2021-10-05 13:11 ` Janosch Frank [this message]
2021-10-05 13:38 ` Christian Borntraeger
2021-09-20 13:24 ` [PATCH v5 03/14] KVM: s390: pv: avoid stalls for kvm_s390_pv_init_vm Claudio Imbrenda
2021-10-05 13:20 ` Janosch Frank
2021-09-20 13:24 ` [PATCH v5 04/14] KVM: s390: pv: avoid stalls when making pages secure Claudio Imbrenda
2021-10-06 15:54 ` Christian Borntraeger
2021-10-06 16:14 ` Claudio Imbrenda
2021-10-12 7:43 ` Janosch Frank
2021-10-12 8:59 ` Christian Borntraeger
2021-09-20 13:24 ` [PATCH v5 05/14] KVM: s390: pv: leak the topmost page table when destroy fails Claudio Imbrenda
2021-10-12 7:58 ` Janosch Frank
2021-10-12 8:33 ` Claudio Imbrenda
2021-09-20 13:24 ` [PATCH v5 06/14] KVM: s390: pv: properly handle page flags for protected guests Claudio Imbrenda
2021-10-12 7:59 ` Janosch Frank
2021-10-26 11:53 ` Christian Borntraeger
2021-09-20 13:24 ` [PATCH v5 07/14] KVM: s390: pv: handle secure storage violations " Claudio Imbrenda
2021-09-20 13:24 ` [PATCH v5 08/14] KVM: s390: pv: handle secure storage exceptions for normal guests Claudio Imbrenda
2021-10-12 8:16 ` Janosch Frank
2021-10-12 8:35 ` Claudio Imbrenda
2021-10-12 12:31 ` Janosch Frank
2021-09-20 13:24 ` [PATCH v5 09/14] KVM: s390: pv: refactor s390_reset_acc Claudio Imbrenda
2021-09-20 13:24 ` [PATCH v5 10/14] KVM: s390: pv: usage counter instead of flag Claudio Imbrenda
2021-09-20 13:24 ` [PATCH v5 11/14] KVM: s390: pv: add export before import Claudio Imbrenda
2021-09-20 13:25 ` [PATCH v5 12/14] KVM: s390: pv: module parameter to fence lazy destroy Claudio Imbrenda
2021-09-20 13:25 ` [PATCH v5 13/14] KVM: s390: pv: lazy destroy for reboot Claudio Imbrenda
2021-09-20 13:25 ` [PATCH v5 14/14] KVM: s390: pv: avoid export before import if possible Claudio Imbrenda
2021-10-05 13:26 ` [PATCH v5 00/14] KVM: s390: pv: implement lazy destroy for reboot Janosch Frank
2021-10-05 14:15 ` Christian Borntraeger
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