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From: Sean Christopherson <seanjc@google.com>
To: Madhavan Srinivasan <maddy@linux.ibm.com>,
	Sean Christopherson <seanjc@google.com>,
	 Paolo Bonzini <pbonzini@redhat.com>
Cc: Nicholas Piggin <npiggin@gmail.com>,
	linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org,
	 linux-kernel@vger.kernel.org, Yosry Ahmed <yosry@kernel.org>
Subject: [PATCH 6/6] KVM: Harden kvm_vcpu_map() against double-mapping and thus leaking references
Date: Thu, 23 Jul 2026 17:47:57 -0700	[thread overview]
Message-ID: <20260724004757.131420-7-seanjc@google.com> (raw)
In-Reply-To: <20260724004757.131420-1-seanjc@google.com>

Now that all on-stack maps use CLASS(kvm_vcpu_map_local), i.e. now that all
maps are zero-allocated, explicitly put any existing mappings/references
when establishing a new mapping to harden against KVM bugs leaking memory,
but yell loudly as the owner of the map is still ultimately responsible for
the lifecycle of the mapping.

Suggested-by: Yosry Ahmed <yosry@kernel.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 virt/kvm/kvm_main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2df8ee9ecf6c..e9e32686e41b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3118,6 +3118,9 @@ int __kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map,
 		.pin = true,
 	};
 
+	if (WARN_ON_ONCE(map->hva))
+		kvm_vcpu_unmap(vcpu, map);
+
 	map->pinned_page = NULL;
 	map->page = NULL;
 	map->hva = NULL;
-- 
2.55.0.229.g6434b31f56-goog


  parent reply	other threads:[~2026-07-24  0:48 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-24  0:47 [PATCH 0/6] KVM: Harden kvm_vcpu_map() usage against memory leaks Sean Christopherson
2026-07-24  0:47 ` [PATCH 1/6] KVM: nVMX: Ensure KVM_REQ_GET_NESTED_STATE_PAGES is cleared on VM-Exit Sean Christopherson
2026-07-24  1:07   ` sashiko-bot
2026-07-24  0:47 ` [PATCH 2/6] KVM: nSVM: Add CLASS()es for automagically handling local kvm_vcpu_map() usage Sean Christopherson
2026-07-24  0:47 ` [PATCH 3/6] KVM: nSVM: Use CLASS(kvm_vcpu_map_local) for SMM VMCB mappings Sean Christopherson
2026-07-24  0:47 ` [PATCH 4/6] KVM: nVMX: Use CLASS(kvm_vcpu_map_local_readonly) for MSR bitmap merging Sean Christopherson
2026-07-24  0:47 ` [PATCH 5/6] KVM: PPC: Use CLASS(kvm_vcpu_map_local_readonly) for patching dcbz Sean Christopherson
2026-07-24  1:03   ` sashiko-bot
2026-07-24  1:15     ` Sean Christopherson
2026-07-24  0:47 ` Sean Christopherson [this message]
2026-07-24  1:11   ` [PATCH 6/6] KVM: Harden kvm_vcpu_map() against double-mapping and thus leaking references sashiko-bot

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