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    Subject[PATCH 5.4 045/108] KVM: PPC: Fix kvm_arch_vcpu_ioctl vcpu_load leak
    Date
    From: Nicholas Piggin <npiggin@gmail.com>

    [ Upstream commit bc4188a2f56e821ea057aca6bf444e138d06c252 ]

    vcpu_put is not called if the user copy fails. This can result in preempt
    notifier corruption and crashes, among other issues.

    Fixes: b3cebfe8c1ca ("KVM: PPC: Move vcpu_load/vcpu_put down to each ioctl case in kvm_arch_vcpu_ioctl")
    Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
    Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
    Link: https://lore.kernel.org/r/20210716024310.164448-2-npiggin@gmail.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/powerpc/kvm/powerpc.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
    index e03c06471678..8dd4d2b83677 100644
    --- a/arch/powerpc/kvm/powerpc.c
    +++ b/arch/powerpc/kvm/powerpc.c
    @@ -2035,9 +2035,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
    {
    struct kvm_enable_cap cap;
    r = -EFAULT;
    - vcpu_load(vcpu);
    if (copy_from_user(&cap, argp, sizeof(cap)))
    goto out;
    + vcpu_load(vcpu);
    r = kvm_vcpu_ioctl_enable_cap(vcpu, &cap);
    vcpu_put(vcpu);
    break;
    @@ -2061,9 +2061,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
    case KVM_DIRTY_TLB: {
    struct kvm_dirty_tlb dirty;
    r = -EFAULT;
    - vcpu_load(vcpu);
    if (copy_from_user(&dirty, argp, sizeof(dirty)))
    goto out;
    + vcpu_load(vcpu);
    r = kvm_vcpu_ioctl_dirty_tlb(vcpu, &dirty);
    vcpu_put(vcpu);
    break;
    --
    2.30.2


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