From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: kvm@vger.kernel.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm-ppc@vger.kernel.org
Subject: [PATCH kernel] KVM: Don't null dereference ops->destroy
Date: Tue, 24 May 2022 05:52:08 +0000 [thread overview]
Message-ID: <20220524055208.1269279-1-aik@ozlabs.ru> (raw)
There are 2 places calling kvm_device_ops::destroy():
1) when creating a KVM device failed;
2) when a VM is destroyed: kvm_destroy_devices() destroys all devices
from &kvm->devices.
All 3 Book3s's interrupt controller KVM devices (XICS, XIVE, XIVE-native)
do not define kvm_device_ops::destroy() and only define release() which
is normally fine as device fds are closed before KVM gets to 2) but
by then the &kvm->devices list is empty.
However Syzkaller manages to trigger 1).
This adds checks in 1) and 2).
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
I could define empty handlers for XICS/XIVE guys but
kvm_ioctl_create_device() already checks for ops->init() so I guess
kvm_device_ops are expected to not have certain handlers.
---
virt/kvm/kvm_main.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f30bb8c16f26..17f698ccddd1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1205,7 +1205,8 @@ static void kvm_destroy_devices(struct kvm *kvm)
*/
list_for_each_entry_safe(dev, tmp, &kvm->devices, vm_node) {
list_del(&dev->vm_node);
- dev->ops->destroy(dev);
+ if (dev->ops->destroy)
+ dev->ops->destroy(dev);
}
}
@@ -4300,7 +4301,8 @@ static int kvm_ioctl_create_device(struct kvm *kvm,
mutex_lock(&kvm->lock);
list_del(&dev->vm_node);
mutex_unlock(&kvm->lock);
- ops->destroy(dev);
+ if (ops->destroy)
+ ops->destroy(dev);
return ret;
}
--
2.30.2
next reply other threads:[~2022-05-24 5:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-24 5:52 Alexey Kardashevskiy [this message]
2022-05-24 20:01 ` [PATCH kernel] KVM: Don't null dereference ops->destroy Sean Christopherson
2022-05-25 1:52 ` Alexey Kardashevskiy
2022-05-25 2:58 ` Alexey Kardashevskiy
2022-05-25 7:47 ` Paolo Bonzini
2022-05-31 4:32 ` Alexey Kardashevskiy
2022-05-31 17:13 ` Paolo Bonzini
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