Re: [PATCH v2 1/9] KVM: PPC: Book3S HV: Fix H_REGISTER_VPA VPA size validation
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2017-08-15 11:24:36
Nicholas Piggin [off-list ref] writes:
KVM currently validates the size of the VPA registered by the client against sizeof(struct lppaca), however we align (and therefore size) that struct to 1kB to avoid crossing a 4kB boundary in the client. PAPR calls for sizes >= 640 bytes to be accepted. Hard code this with a comment. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kvm/book3s_hv.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
This one should go via Paul. Hopefully he can just pick it up. cheers
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 359c79cdf0cc..1182cfd79857 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c@@ -485,7 +485,13 @@ static unsigned long do_h_register_vpa(struct kvm_vcpu *vcpu, switch (subfunc) { case H_VPA_REG_VPA: /* register VPA */ - if (len < sizeof(struct lppaca)) + /* + * The size of our lppaca is 1kB because of the way we align + * it for the guest to avoid crossing a 4kB boundary. We only + * use 640 bytes of the structure though, so we should accept + * clients that set a size of 640. + */ + if (len < 640) break; vpap = &tvcpu->arch.vpa; err = 0;-- 2.13.3