From: Nicholas Piggin npiggin@gmail.com
stable inclusion from linux-4.19.199 commit 9bafc34dc4ad0cef18727c557f21ed3c3304df50
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[ 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 Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- 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 02a4bf1cc1170..48bd3fb87c82e 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -1994,9 +1994,9 @@ 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; @@ -2020,9 +2020,9 @@ 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;