[SRU][J][PATCH v2 2/2] KVM: arm64: Tear down vGIC on failed vCPU creation

[Massimiliano Pellizzer]

From: Will Deacon <will at kernel.org>

If kvm_arch_vcpu_create() fails to share the vCPU page with the
hypervisor, we propagate the error back to the ioctl but leave the
vGIC vCPU data initialised. Note only does this leak the corresponding
memory when the vCPU is destroyed but it can also lead to use-after-free
if the redistributor device handling tries to walk into the vCPU.

Add the missing cleanup to kvm_arch_vcpu_create(), ensuring that the
vGIC vCPU structures are destroyed on error.

Cc: <stable at vger.kernel.org>
Cc: Marc Zyngier <maz at kernel.org>
Cc: Oliver Upton <oliver.upton at linux.dev>
Cc: Quentin Perret <qperret at google.com>
Signed-off-by: Will Deacon <will at kernel.org>
Reviewed-by: Marc Zyngier <maz at kernel.org>
Link: https://lore.kernel.org/r/20250314133409.9123-1-will@kernel.org
Signed-off-by: Oliver Upton <oliver.upton at linux.dev>
(backported from commit 250f25367b58d8c65a1b060a2dda037eea09a672)
[mpellizzer: context adjusted due to missing commit
 3f868e142c0bb (“KVM: arm64: Introduce kvm_share_hyp()”)]
CVE-2025-37849
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 arch/arm64/kvm/arm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 4a1f6f93474a5..89ee72e182539 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -333,7 +333,11 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 	if (err)
 		return err;
 
-	return create_hyp_mappings(vcpu, vcpu + 1, PAGE_HYP);
+	err = create_hyp_mappings(vcpu, vcpu + 1, PAGE_HYP);
+	if (err)
+		kvm_vgic_vcpu_destroy(vcpu);
+
+	return err;
 }
 
 void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
-- 
2.51.0