Thread (3 messages) 3 messages, 2 authors, 2021-07-21

[PATCH 2/2] KVM: PPC: Fix kvm_arch_vcpu_ioctl vcpu_load leak

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STALE1921d LANDED

From: Nicholas Piggin <npiggin@gmail.com>
Date: 2021-07-16 02:44:17
Subsystem: kernel virtual machine for powerpc (kvm/powerpc), linux for powerpc (32-bit and 64-bit), the rest · Maintainers: Madhavan Srinivasan, Linus Torvalds

Landed in mainline as bc4188a2f56e on 2021-07-17.

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

Reported-by: Alexey Kardashevskiy <redacted>
Fixes: b3cebfe8c1ca ("KVM: PPC: Move vcpu_load/vcpu_put down to each ioctl case in kvm_arch_vcpu_ioctl")
Signed-off-by: Nicholas Piggin <npiggin@gmail.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 be33b5321a76..b4e6f70b97b9 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -2048,9 +2048,9 @@ 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;
@@ -2074,9 +2074,9 @@ 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;
-- 
2.23.0
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