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Message-Id: <20220614021158.1101574-1-sashal@kernel.org>
Date: Mon, 13 Jun 2022 22:11:58 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Alexey Kardashevskiy <aik@...abs.ru>,
Paolo Bonzini <pbonzini@...hat.com>,
Sasha Levin <sashal@...nel.org>, kvm@...r.kernel.org
Subject: [PATCH MANUALSEL 5.4] KVM: Don't null dereference ops->destroy
From: Alexey Kardashevskiy <aik@...abs.ru>
[ Upstream commit e8bc2427018826e02add7b0ed0fc625a60390ae5 ]
A KVM device cleanup happens in either of two callbacks:
1) destroy() which is called when the VM is being destroyed;
2) release() which is called when a device fd is closed.
Most KVM devices use 1) but Book3s's interrupt controller KVM devices
(XICS, XIVE, XIVE-native) use 2) as they need to close and reopen during
the machine execution. The error handling in kvm_ioctl_create_device()
assumes destroy() is always defined which leads to NULL dereference as
discovered by Syzkaller.
This adds a checks for destroy!=NULL and adds a missing release().
This is not changing kvm_destroy_devices() as devices with defined
release() should have been removed from the KVM devices list by then.
Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
virt/kvm/kvm_main.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 287444e52ccf..4b445dddb798 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3329,8 +3329,11 @@ static int kvm_ioctl_create_device(struct kvm *kvm,
kvm_put_kvm(kvm);
mutex_lock(&kvm->lock);
list_del(&dev->vm_node);
+ if (ops->release)
+ ops->release(dev);
mutex_unlock(&kvm->lock);
- ops->destroy(dev);
+ if (ops->destroy)
+ ops->destroy(dev);
return ret;
}
--
2.35.1
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