[PATCH 5.4 045/108] KVM: PPC: Fix kvm_arch_vcpu_ioctl vcpu_load leak

Greg Kroah-Hartman
2021-07-26T16:05:53Z

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