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    Subject[PATCH 4.4 18/74] arm/arm64: KVM: Fix ioctl error handling
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Michael S. Tsirkin <mst@redhat.com>

    commit 4cad67fca3fc952d6f2ed9e799621f07666a560f upstream.

    Calling return copy_to_user(...) in an ioctl will not
    do the right thing if there's a pagefault:
    copy_to_user returns the number of bytes not copied
    in this case.

    Fix up kvm to do
    return copy_to_user(...)) ? -EFAULT : 0;

    everywhere.

    Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
    Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
    Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/arm/kvm/guest.c | 2 +-
    arch/arm64/kvm/guest.c | 2 +-
    2 files changed, 2 insertions(+), 2 deletions(-)

    --- a/arch/arm/kvm/guest.c
    +++ b/arch/arm/kvm/guest.c
    @@ -155,7 +155,7 @@ static int get_timer_reg(struct kvm_vcpu
    u64 val;

    val = kvm_arm_timer_get_reg(vcpu, reg->id);
    - return copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id));
    + return copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)) ? -EFAULT : 0;
    }

    static unsigned long num_core_regs(void)
    --- a/arch/arm64/kvm/guest.c
    +++ b/arch/arm64/kvm/guest.c
    @@ -186,7 +186,7 @@ static int get_timer_reg(struct kvm_vcpu
    u64 val;

    val = kvm_arm_timer_get_reg(vcpu, reg->id);
    - return copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id));
    + return copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)) ? -EFAULT : 0;
    }

    /**

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