From: Nicholas Piggin <npiggin@gmail.com>
Date: Fri, 16 Jul 2021 02:43:10 +0000 (+1000)
Subject: KVM: PPC: Fix kvm_arch_vcpu_ioctl vcpu_load leak
X-Git-Tag: v4.19.199~45
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=9bafc34dc4ad0cef18727c557f21ed3c3304df50;p=thirdparty%2Fkernel%2Fstable.git

KVM: PPC: Fix kvm_arch_vcpu_ioctl vcpu_load leak

[ 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>
---

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 7c8354dfe80e2..ad5a871a6cbfd 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -1995,9 +1995,9 @@ 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;
@@ -2021,9 +2021,9 @@ 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;